using Programming;

A Blog about some of the intrinsics related to programming and how one can get the best out of various languages.

Getting started with programming and getting absolutely nowhere (Part 3)

Since we've made something, let's make it cooler

Lesson 2: Now That We're Programmers, Let's Make Something
Lesson 4: Moving on to Solving Business Problems

Now that we've built something that actually resembles a business problem, and I want to take this time to show you one of the coolest features of F# in my opinion. So in this post, I want to introduce the conecpt of a "DSL", or a "domain-specific language".

F# has a very powerful feature that allows you to create your own operators. What do I mean by operators? Things like +, or -, or the |> operator. You can build your own, which leads to building your own DSL.

What, exactly, is a DSL?

I mentioned the name "domain-specific language", but I know without context that has little meaning, so let's clarify. By building our own DSL we're actually creating a language that is a subset of another language. We're creating our own language! We don't even have to do much to make it happen, so let's investigate that a little bit.

First off, a DSL isn't always apporpriate, you need to take care to understand what a DSL applies to, and when to use it. As a language, F# already has a lot of operators, including some confusing ones, so adding more to the mix is probably not the greatest idea unless it makes sense, and it's going to be used a lot.

In work I've actually done this, and I'm going to show off the operator I created, how it works, and how you can create one. It's really quite simple, and if you've tried experimenting with the language you probably already learned that it's possible, and may have created one yourself. If so, congrats! That's awesome! You clearly figured it out faster than me, and I applaud you for that, because I didn't figure this out until a very long time after I started using F#.

Let's make a DSL

Seriously, let's create one. Remember that split function we built before? It was pretty basic, wasn't it? We took a char and a string, and we split apporpriately, but it's about time for us to make it a little easier.

In the work I do we do a lot of string parsing, which means a lot of calling split. In fact, I do it so often that I have a String.fs library file, that has this (and a few other) nifty functions in it. I carry that library to all my F# projects, and it saves me a great deal of time.

let split (c:char) (s:string) = s.Split(c)

Remember this method? Pretty basic, take a string and split on the char. We can partially apply it, even, to make it simpler if we're splitting on the same string a lot. Now what if I told you we could build our own operator to make this work? What if we could create something like:

let splitString = someString <|> someChar

Notice the <|> operator? Try to use it in F# right now, you probably can't. (Unless you already created it, then feel free to use it.) Because I'm a nice person I'm going to just give you this operator for free.

let (<|>) (s:string) (c:char) = s |> split c

It is that complex, adding your own operator is as easy as defining a function with the operator in parenthesis as the function name. We could literally create anything, the issue is, should we?

Uh oh - here be dragons, errr...dinosaurs

Be careful when defining a DSL

DSL's can be powerful things - they can make complex things simple, and they can make simple things complex. You want to define a DSL that fits, and a DSL that is powerful. Don't define a DSL "just because you can" - I've done so, bad idea.

However, if you define a DSL well. you can turn something increasingly complex into a much simpler feeling, it feels like a built-in operator. It feels like it belongs. It just feels natural.

Since this post is coming out on a Friday (at least here in the Eastern Time Zone - could easily be Saturday for many of you) you probably don't have to work tomorrow (or today, if it's already Saturday), so if you get a chance, experiment with custom operators. Try to figure out how they work, this one little feature can truly make things easy on you. Shoot, you can even try to build the opposite operator: >|< if you like, it should fit in with the code below. (Though in my real DSL for this, the operator is actually ><, but I demonstrated it as >|< since that's more directly transpated as the opposite of what we have.)

let names =
    rawNames <|> ' '
    |> Array.toList
    |> List.fold (fun (acc:string list) str ->
        match acc with
        | prev::tail when prev.Length <= 3 -> (prev >|< " " >|< str)::tail
        | _ -> str::acc) []
    |> List.rev
    |> Array.ofList

Bonus day: documentation

We've gone through writing some code, but the biggest thing people get caught up on is writing documentation. Now, on one hand, I'm a firm believer that good code documents itself. On the other hand, I know that I very infrequently write good code. So we always need a way to tell the "consumer" (often times ourselves, but if you're working on some API think of the people who will be using it) what to do with our method/function/variable/thing. This comes in many forms, one of which is the Visual Studio / F# documentation comments.

Have you ever wondered how people can put text into the intellisense-hover-dealy of the function/variable/parameter they provide? It's actually quite easy, and in F# it's trivial: use a triple-slash comment: ///.

/// Splits a string into an array on the specified char.
let (<|>) (s:string) (c:char) = s |> split c

Now when we hover any instance of our <|> operator, we should see that string show up:

Woah - its like magic

Damn that's cool. If you're building an F# project, you can also generate an XML file with all the triple-slash comment docs in it. Simply open the project properties, go to "Build" and check the "XML Documentation File" box. Visual Studio will then generate a .xml file in the same directory as your .exe/.dll that contains these comments in a form that Visual Studio can understand, and that can be used to generate web documentation. (This is part of how MSDN is built - the code comment documentation becomes the web documentation.)


As an aside, I want to tell you all how grateful I am to have met some of the developer comrades I have - a lot of them have been extremely helpful to me regarding programming, software development in general, and even doing things right.I was actually thinking about each one of them as I wrote this, and I would call them out by name but I don't want to reveal any personal information, so for those of you that I'm referring to (and you all know who you are): thank you.

Getting started with programming and getting absolutely nowhere (Part 2)

Now that we're programmers, let's make something

Lesson 1: How To Become a Programmer (In a Few Not-So-Easy Steps)
Lesson 3: Since We've Made Something, Let's Make It Cooler

So two days ago I posted a very rudimentary introduction into "how to become a programmer", which was mostly a rant about what is and isn't important, and about how F# works. (Why F#? Because it lets us be lazy, and it does a whole hell-of-a-lot for you.)

Today we're going to introduce the business domain.

Almost everything is "business logic"

The first thing about the "business domain" is that it's a very real thing. In the business domain everything is what's called "business logic", that is: logic that makes the business work. Now we're not talking "business" as in "for-profit corporate entity", but "business" as in "a person's concern". (Think: "it's none of my business".)

Basically, business logic is any logic that is related to the task at hand. So consider a "cart" system, business logic might be "we need to be able to add an item to the cart, remove an item from the cart, and change quantities of items in the cart." Simple, right? Somewhat straightforward. You may also here this referred to as "BL" or "domain logic", or the collective "domain" (which includes the "business domain" and the "business logic"). I'm going to call it "business logic" because that's what is most applicable to my situation, but feel free to use whatever terms you feel appropriate.

So we saw an example of business logic, what do we do with business logic? Usually we write our software around the business logic, so we may write a function addItemToCart or removeItemFromCart that adjusts the items in our cart as appropriate. These are considered "functions that perform business logic".

Simple, right? This is all largely basic, but it's important to know because we need to understand what is and isn't business logic. For example, when we disucss the implementation itself, we're no longer talking about business logic, but "application logic". The business logic is the broader picture: what is the purpose of our application? It's the "problem" the application is "solving", this can vary all over the place, but the basic idea is it's the higher-overview of the application.

All that long-worded rambling aside, let's define a piece of business logic that we want to build an application to solve:

Given a string, split it into a group of "words" on spaces, where each "word" has no-less-than three characters.

This is a very real problem I had to solve for my job recently, I won't say why, but it was necessary. So, we're going to focus specifically on this problem in this post.

The first step is to define the sub-steps

Every problem is, at it's core, a series of smaller problems. You can always break it down, though sometimes it's unecessary. For our problem let's break it down into subparts:

  1. Split a string on spaces
  2. Analyze the first word, if it has 3 or fewer characters, group it with the next word
  3. Repeat for the next word

So that's more manageable, and we can solve that in "sub-steps". We can solve each step independently. (Granted, we only have 3 steps, but we'll break step 2 down futher when we get to it.) Each step should be testable: so given some input I should have a defined output.

Splitting a string on spaces

So the first step is actually the easiest, split the string on spaces. in F# this is easily done via String.Split, which is available in the entire .NET framework:

let parts = "Some String With A Short Word".Split(' ')

So that's easy, and we can create a function that handles that pretty easily, we'll define a split function that takes a string, and a char (separator) and splits the string on the "char" (separator):

let split (c:char) (s:string) =
    s.Split(c)

That's pretty basic, but why did we define a new function when we could just call s.Split(c) directly, with our own s and c? This is so that we can split strings "idiomatically", that is, matching the general style of F# code. F# isn't about calling methods, it's about composing functions, and you cannot compose String.Split(char) easily like that, so we define a function that lets us do so.

So now we could test our function, which involves simply calling it:

let parts = "Some String With A Short Word" |> split ' '

Well that was easy. This shows that we can pipe a string into the split function, and it does what we expect.

Moving to Step 2: this is going to hurt

So F# makes step 2 pretty easy, and if you have any programming experience with a non-functional language, I want you to forget it right now. What you think you know is not true in F#, and we need to redefine the problem.

We can break step 2 down a little further:

  1. Get a word
  2. Check how many characters the word has
  3. If < 3, it belongs with the next word

So let's start building a groupWords function, we're going to do this the "Elliott Brown" style, which is probably different from what you've usually seen, but this is where functional languages make things pretty awesome.

Instead of looking at the current word, we're going to look at the previous word, since it makes things easier. We're going to use a basic pattern match with a guard clause, List.fold, Array.toList, and Array.ofList.

The easiest way to do this involves converting the string array to a string list, which is done with the Array.toList:

let stringList = parts |> Array.toList

If you're following along in a REPL (the F# interactive window), you should notice the biggest difference between the printed versions of each is that Array has vertical-pipes on the inside of the brackets: [|element1; element2; ...|], and List does not: [element1; element2; ...].

So now we're going to fold over that list: a fold takes an accumulator, and a value. It iterates over each value in the List and applies a function to it, which usually combines the value with the accumulator somehow. Our fold is pretty basic:

let groupStrings (acc:string list) str =
    match acc with
    | prev::tail when prev.Length <= 3 -> (sprintf "%s %s" prev str)::tail
    | _ -> str::acc
let groupedStrings = stringList |> List.fold groupStrings []

We could modify this to take a length instead of 3, but I'll leave that up to you.

Some neat syntax things:

  1. The match is a "pattern match", similar to a C-style language switch, but on sterroids.
  2. The prev::tail is a pattern expression for a list: it means "match the first element in the list to prev, and the remaining elements to tail.
  3. The when ... is a "guard clause": it means this expression is matched first, then the entire pattern is matched if and only if the guard clause returns true.
  4. The -> means "return the right side as the result of the match expression." (Basically)
  5. The (sprintf "%s %s" prev str) just combines the two strings with a space between them.
  6. The ::tail now creates a new list with the sprintf block as the first element, and the remaining elements as the, well, remaining elements.
  7. The _ is a "match anything" pattern-expression.
  8. The [] is an empty list (the type is inferred to be whatever that "folder" expects - a string list in this case).

Now we just need to reverse the list, which in F# is easily achieved by List.rev:

let finalResults = groupedStrings |> List.rev

And lastly, we'll convert them back to an array with Array.ofList:

let result = Array.ofList

That's it, make it reusable

So now we've successfully built the functions to do this work, let's build a function that is reusable.

let splitAndGroupString =
    split ' '
    >> Array.toList
    >> List.fold (fun (acc:string list) str ->
        match acc with
        | prev::tail when prev.Length <= 3 -> (sprintf "%s %s" prev str)::tail
        | _ -> str::acc) []
    >> List.rev
    >> Array.ofList

And we can call it as:

let splitStr = "Some String With A Short Word" |> splitAndGroupString

And that's it!

We went through some basic business logic today, we'll be going through more complex stuff in the coming lessons, but it's good to take it slow (at first), and we'll eventually build up to some pretty complex operations.

I told you I would get more organized, and I did. As we continue I'll figure out how I plan to present things effectively, but for now I'm just going to stick with my gut. I hope you enjoyed it and learned something, but if not it's still helping me learn more and become a better software engineer, so you should probably count on more crap coming from me here soon.

Getting started with programming and getting absolutely nowhere (Part 1)

How to become a programmer (in a few not-so-easy steps)

Lesson 2: Now That We're Programmers, Let's Make Something

Recently a friend of mine has asked me to teach him "how to become a programmer", which is not really an easy task to accomplish, but I'll give it a shot. Since I'm an altruistic person, I am going to make this a series of blog posts on the idea of becoming a programmer, we're going to mostly look at the .NET structure, and the first few lessons will be in F# to get the ball rolling somewhat quickly.

The first rule of programming: forget what you think you know

All programmers, including myself, start somewhere. The biggest mistake I've made on the quest to become a programmer is to focus entirely on some "bigger goal" to achieve, some large project that I wanted to build or work on. Goals are great, but we have to start small. (Especially in the modern world, where we have hundreds of languages and frameworks and environments to choose from.)

So my very first word of wisdom is to forget everything you think you know. All of it. Forget what languages you think you want to learn, forget what areas you want to work in, forget what you know about "HTML coding for Myspace pages", ditch it all. We're going to start your career of programming from the beginning - the basics first, then we'll work up to the fun things.

"Hello World" is so cliche

I'm not going to bore you by starting our adventure with a "Hello World" program, instead we're going to start it from an actual business-driven design. Instead of contriving highly-egregious examples of programs to write, building some sort of "example" application, we're going to build real-world business applications: things that you will actually be expected to come up with. And we're going to do so poorly, so that we can learn where to improve. I'm going to take personal experiences (and mistakes) and burn them into your core, so that you can identify what makes good code good, and what makes bad code bad.

The first mistake is that people always lose interest, as you probably have by this point in this blog post. But hang tight, we have some code coming up, and I'm going to start showing you how we can take some basic, elementary ideas and turn them into truly remarkable pieces of software.

Without further ado, let's get going

We're going to begin our entourage into programming with F#, which is very much unusual from normal adventures. The easiest way to get started is to install a copy of Visual Studio 2017 Community (or if you prefer to purchase it, Enterprise or Pro), with the F# development tools selected. I'm not going to walk you through this for a few reasons:

  1. There are about a hundred thousand articles and blog posts on installing Visual Studio and adding and removing features.
  2. It's actually extremely self-explanatory, it really is pretty simple to get set up.
  3. I want you to struggle a bit with this.

Notice point 3: I'm not going to hold your hand, we're going to go on an adventure and we're all going to make mistakes, I want you to struggle with this entire venture, for two reasons on it's own:

  1. Only by struggling do you force yourself to think critically;
  2. I want you to decide if this is a path you wish to pursue.

Too many people say "teach me to be a great programmer" but refuse to put the work in to become one - I can't write a long, wordy article that makes you a good programmer, I can only guide you down the path to success. It is up to you to decide if you wish to continue down the path or not. By forcing you to struggle with real-world problems you'll be better prepared for how programming actually is.

So let's start with some code. Because we're using F# it's going to be a somewhat quick foray into our career, so open up Visual Studio, and find the F# Interactive window - I won't tell you where it is, so this is the first struggle you'll have to do on your own. (I'll give you a hint - it's under some sort of "Window" menu somewhere.)

Once we've opened F# Interactive, I want you to define some sort of "domain model" to describe some sort of arbitrary user. The F# syntax for such a thing is something like:

type SomeName = {
    SomeProperty
}

The syntax for SomeProperty can look something like:

SomeValue : SomeType

Right, so I'll give you the first object for free:

type User = {
    Id : int
    Name : string
    Email : string
    Phone : string option
}

For those of you who don't know, this is the basic F# syntax for defining a "class", but we get a lot more than just a class, so we won't call it such a thing (because naming is important - if it's not a duck we really ought not call it a duck). In F# this is called a Record.

A Record in F# has a few basic features: properties/fields, values, and is non-nullable. In fact, almost everything in F# is non-nullable which is why we're starting with this language. Nullable values are hard, and if you don't believe me just "Google" for a "NullReferenceException" - it should become clear.

What we've define here is a "User" with four properties: an "Id" (which is an integer: a whole number so-to-speak), a "Name" (which is a string, or a sequence of characters in a specific order), an "Email" (which is also a string), and a "Phone" (which is a string, but it's "optional" - we may or may not have a phone defined). An "option" in F# is a kind of null, but not really. It has two cases: a None value (which means the lack of a value entirely), or a Some value, which means that there is "Some" value there. These are important because these idiomatically represent the idea of a non-existent value.

One of my favourite features of F# is it's type-inference, that is, F# will detect what types you're playing with in most situations correctly. So we're going to define a "User" now, the syntax of which is:

let myUser = {
    Id = 1
    Name = "Elliott"
    Email = "example@example.com"
    Phone = None
}

I believe I owe you an explanation: by specifying all four of these properties, F# understands that we want to create a User object. We didn't explicitly tell it that, but it assumed based on what we gave it that we wanted that type of object. We could have also told it that we wanted myUser to be a User with a type-annotation, that is, : SomeType, which would mean let myUser : User = {...} would create our myUser record. Simple, right?

Pointing out our First Mistake

I need to tell you that we already made a few mistakes here, not the least of which is the choice of myUser as a name. What does myUser mean? Why does it have the type-name in it? What will myUser be doing?

We really need to touch on naming, but I don't have a lot of time for that, so I'll be brief: naming things is hard. You should name something for what it means, rather than what it is. That is, instead of myUser, we should really name that ebrown, or something.

We also need to touch on the type-safety (which is one of many such safeties) in F#. As a language, F# forces you to define the entirety of a type at once. We know that Phone has a value of None, which happens to be the default, but we still have to tell F# that we want to set None explicitly to Phone. It won't do it by itself, we have to. Remove that line and you'll see what I'm talking about.

So what have we effectively done here? We've created a Type, but what is a type? What does it do? To put it short, we've created a point that we can hold data. So that's a good thing, right? We've created something that can store state, something that holds a group of related values. We could have just as easily done

let ebrownId = 1
let ebrownName = "Elliott"
let ebrownEmail = "example@example.com"
let ebrownPhone = None

So what's the difference? Why did we build a type? I'll give you a hint: what stops you from sending ebrownId, ebrownName, alexEmail, ralphPhone to a method? Ah, that's what it's for. It groups related values together so they're unmistakeably related. They belong in a group.

Alright, so I've done a lot of talking (see: rambling), and we've effectively seen what, 20 lines of code? Let's actually make something happen. I'm not going to explain every little detail of this next snippet, but I will go over the general idea.

type User = {
    Id : int
    Name : string
    Email : string
    Phone : string option
}

let ebrown = {
    Id = 1
    Name = "Elliott"
    Email = "example@example.com"
    Phone = None
}

let createReminder thing user =
    sprintf "Hello %s, this is a reminder to do the thing (%s)." user.Name thing

let remind =
    createReminder "Write a Blog Post" >> printfn "%s"

let reminder =
    ebrown |> remind

Right, so what happened? This is actually pretty simple, we already saw creating a user, now all we're adding is passing that user to a function and gathering a result. There are a couple key points to note here:

The pipe-right (|>) operator takes the value on the left side, and transforms it to be the last argument of the function on the right side. So ebrown |> remind is the same as remind ebrown. We use this pipe-right operator mostly to keep the order of things consistent. I.e. let someResult = someValue |> step1 |> step2 |> step3, thus allowing us to follow the "flow" of the functions.

The next notable piece is the compose-right (>>) operator, this has a similar effect as the pipe-right, except that instead of needing a value, it needs a function. So it builds a function that is composed of the steps of the first function, then the second function. This can also be chained as necessary, the difference between this and pipe-right being what they operate on: pipe-right operates on the value, compose-right operates on the function.

This brings us to an interesting aspect of F#: the type system. I've deliberately avoided discussing it yet, but now it's about time to get into the nitty-gritty of what the type-system does.

In most "regular" languages functions are presented as some type of prototype: you have an input and a result. This is usually written (in C-based languages) as ResultTypeName FunctionName(InputTypeName1 inputValue1, InputTypeName2 inputValue2, ...), etc., which basically says "this function takes [...] as input and returns a ....".

In F# we do things a little differently. Instead of declaring a function as having "all these" inputs each and every function in F# has exactly one input.

But Elliott, our createReminder takes two parameters, a thing and a user.

Technically, this is wrong. The createReminder function takes one input, then a new function is created which takes the second input. We call this "currying", in laymans terms it means that functions are partially applied, which is, kind of, part of the point of being a functional language.

Type Definitions aren't so scary

Enough blab, let's talk about a type definition. F# defines a function as 'a -> 'b, that is, 'a is an input which returns a 'b. If you look at the signature for our createReminder, you'll see that it is string -> User -> string, "I first take a string, which returns a function that takes a User, which returns a string."

If you look at remind, you'll see a very different signature: User -> unit. In F# the unit is the "void" type, that is, a unit is a nothing. It's basically the end of something. You can create a unit directly as (). If you run let unitThing = () in F# Interactive, you'll see it prints val unitThing : unit = (), meaning it's a nothing. So remind takes a User and returns a "nothing".

So, all this said, we can build a reasonable thought process from the following signatures:

string -> int -> unit            // Takes a string, then an int, returns a unit / nothing
string -> string -> string       // Takes a string, then a string, returns a string
int -> (string -> int) -> unit   // Takes a string, then a `string -> int` function, returns a nothing
(string -> int) -> float         // Takes a `string -> int` function, returns a float

Do those make sense? Good, I hope you thought that was easy, because I'm only going to make things more difficult from here.

What the snot does any of this do?

I want to intentionally confuse you for a moment, because learning requires a struggle. We're going to look at a highly contrived example (remember when I said I wouldn't do that? I'm breaking that rule apparently) of just how complex we can get.

let formula values =
    let xb =
        values
        |> List.sum
        |> (/)
        <| (values.Length |> float)
    values
    |> List.fold (fun acc x -> acc + (x - xb) * (x - xb)) 0.
    |> (/)
    <| (values.Length |> float) - 1.
    |> System.Math.Sqrt

Oh boy. This looks fun. Can anyone guess what's going on here? If you guessed this calculates the sample-standard deviation, you're spot on. We simply let xb be the average (calculated by summing the values, then divide by the length), then we simple "fold" over the values, summing the squares of x - xBar together, divide by N - 1 and then take the square-root.

You should have been able to guess that the pipe-left (<|) operator does what the pipe-right operator does, but in reverse. Instead of supplying the right side as the last argument to the left call, it supplies the left side as the last argument to the right call. Do note that nothing is special about the division (/) operator, we can actually treat operators as functions in F#. That is the biggest take-away from this.

We'll also notice this function has a type-definition of float list -> float.

Building an order of elements

I'm going to keep on the boring train for the rest of this section, since we're already there. (My rambling doesn't help.) We're going to discuss greating a list/array/sequence. (All three of these are different ways to represent a grouping of values that share a type.)

The most basic of these types is an Array, which is also an array and a []. All three of these are valid ways to state "array". Arrays are one of the most basic "collection" structures. Essentially, you declare an array (of a fixed size) and then set elements in it by "index" (0-based). In F# we access an array element by .[#], where # is the index (with the first being index 0) of the element we want.

Think of an array as a crayon box: you have a specific number of crayons (each of a different color) which you can access by "index" (or position). Simple, right? We could even represent a crayon box in F#:

let crayons : System.Drawing.Color array = ...

Pretty simple. You can construct an array of elements by wrapping them in [|...|], and separating each element by a semicolon. ([|System.Drawing.Color.Black; System.Drawing.Color.Gray; ...|]).

Next is a List or list. This is simply an Array that can be resized. The syntax is [...], with the same semicolon separator.

Finally, a sequence. This is a very special collection in that it's lazy. The syntax is {...} with the semi-colon separator. The thing about a Sequence (or seq) is that it doesn't initiate all the values initially, it only initiates them when you iterate them. (That is, ask for the next value.) While a list and array both allow you to index a value, a sequence does not. Remember this, because we'll need them later.


I'm going to stop here, but I'm going to pick up where I stopped here tomorrow, and we'll go over a couple business domain issues and learn how to build software to represent them. I'll be doing a lot of "here's how you solve the problem, each step of the code" and not a lot of "this is what _ means", so I expect you to research the different operations that we do, and try and use some critical thinking to push yourself to learn what's going on.

I do realize that this was probably the worst possible writing ever by me, but it's been a while since I've done one of these and I tried to just cover what I could as I thought of it. The next few sections of the series will get a lot more informative and organized.

Phishing: how do we identify it?

Holy phishing batman

Note: this will be part of a longer series on identifying, preventing, and remedying issues related to phishing attempts.

I don't usually post about issues like this, but this is a huge problem and can definitely ruin people's lives, I think it's important to get more information on the topic out there.


So recently I tweeted about two very obscure phishing scams I was sent:

Recently I got two very good-looking phishing emails, annotated to help future potential victims identify them and prevent scams.

It was obvious to me that they were scams, based on all the tell-tale signs of the email I was immediately thrown to the fact that they were not legitimate emails from either of these organizations. (I happen to have accounts with both of them, which made identification slightly easier.)

We're in the year 2017, and if anyone tells you Email or computer systems are dying then they're absolutely wrong. We're entering an age where the internet is becoming a necessary requirement for anyone's life, and I want to talk about one of the biggest problems with email: phishing,

What is phishing?

When I went to college (and even before then) we studied a term called 'social engineering', that is, the idea that an attacker will not attempt to hack/crack/break into your system through technical means, but will convince you to do it for them. This is the broader category that phishing fits into.

Phishing is the act of an attacker convincing a victim (usually a user) to deliver secured information to them in a means that makes the victim completely unaware that they just gave secure information away through the use of faked online forms/websites/emails. The most common (in my experience) is banking information.

With all this in mind, I want to try to help you prevent becoming a victim. There isn't a true "guide" for how you can stop yourself from becoming a victim, but there are steps you can take. I'm going to use actual phishing emails I was sent for this demonstration. Real emails you may receive and how you can identify them and prevent yourself from becoming a victim.

Do note: I'm not even going to talk about the technical aspects of these emails, this guide will be an end-user guide, for the people these emails are designed to victimize.

What does phishing look like?

To see what phishing looks like we're going to use two very real examples, which I've already annotated with some of the tell-tale signs of a phishing email (any one of these signs on it's own isn't necessarily an indicator, but all of them together add up quickly).

Screenshot 1 - Wells Fargo Phishing Attempt Screenshot 2 - Capital One Phishing Attempt

As you can see, I drew a lot of red. Let's talk about this section by section to explore how we can apply this more broadly.


The Wells Fargo email broke down

The first image is from 'Wells Fargo' (or someone that wants you to think they're Wells Fargo). We can see an issue with this right off the bat: the 'From' address. I happen to be a Wells Fargo customer (funny: the email that this phishing scam was sent to is not my account email), and all the emails I get from them have a specific from address: Wells Fargo Online <alerts@notify.wellsfargo.com>. So of course that was the first big red flag for me. However, let's assume you don't know that the usual alert email is alerts@notify.wellsfargo.com, the address itself has one fatal flaw that should give you at least a yellow flag:

wellsfargo_notification_alerts@wellsfargo.com

Generally a bank won't send you an email from bankname_notification_alerts@bankname.com, that's not their usual M.O., typically the email address is just notifications@bankname.com or alerts@bankname.com.

So let's assume that the sender address isn't the problem, that's fine. We'll move to the 'To' line. They sent this email To: Recipients. If you are using Outlook you can expand the contact card and you'll find that the Recipients email address is wellsfargo_notification_alerts@wellsfargo.com. So the attacker sent the email to themselves, and they must have blind-carbon-copied us on it. That immediately tells me it's a phishing attempt. Why would my bank send an email to itself and blind copy me in?

If that wasn't obvious enough, and for some reason you're still in the yellow zone, we have this attachment named Wells Fargo Online Verification.htm.

For those of you that aren't technical users: an htm document is synonymous for an html document, which is basically a webpage. (It is a webpage, but it's not on the web at this point, it's on your PC.) This type of document can easily be processed by a web-browser on your computer (Internet Explorer, Mozilla Firefox, Apple Safari, Opera, Microsoft Edge, Google Chrome) and can do many very cool things, and also many very bad things.

The problem is most people aren't aware of what to do with these documents, so they're not used much for actions with the end-user. Generally you can just double-click the document and it will open in your browser of choice, whatever your default is.

Professional organizations don't usually send you these types of documents. Usually when this type of information needs to be sent you get one of two things: a link to a web-page or a PDF file. Why? Because msot people know what to do with both of those. They know to click a link, and they know to download/save/print a PDF.

The problem with HTML files is that they can contain malicious data. (There are more technical terms for it, but I'll save you the hassle.) They can install files on your PC, they can change settings (in some cases), and they can make you think you're going to a legitimate banking website.

We're not going to open it yet, we're going to mark it as a red flag and continue with the email.

The next thing we see that's a moderately yellow flag is the email body. There is a lot of text in this body that rubs me the wrong way.

We recently reviewed your account, and we are suspecting that your Wells Fargo account may have been accessed from an unauthorized computer.

This may be due to changes in your IP address or location. Protecting the security of your account and of the Wells Fargo network is our primary concern.

We are asking you to immediately login and report any unauthorized withdrawals, and check your account profile to make sure no changes have been made.

This alone isn't a bad phrase, but when it's combined with the next phrase it becomes more disturbing:

To protect your account please follow the instructions below:

  • LOG OFF AFTER USING YOUR ONLINE ACCOUNT

If it were truly a security concern, the bank wouldn't just recommend logging off after you finish using your account. They would also recommend changing your credentials. If your account is being accessed by another PC/user then logging off will not fix it. (In almost all cases, this is true.) So, if the sender were truly concerned about your information, as a bank would be, the recommendation would be to change your password.

Please Download the Attachment file of your Wells Fargo Online Verification and Open on on a browser to complete your account verification process:

Verify the information you entered is correct.

We apologize for any inconvenience this may cause, and appreciate your support in helping us maintaining the integrity of the entire Wells Fargo System. Please verify your account as soon as possible.

Why would I need to download an attachment to login? If I simply need to login to my account, send me a URL/address.

Lastly:

Copyright © 1999 - 2016 Wells Fargo. All rights reserved..

No self-respecting bank would leave that double-period typo in an email. Bank emails go through a rigorous approval process, that typo alone isn't justification for a phishing attempt, but when added to the rest of the email, 'Mark as Spam'.


Breaking down the Capital One attempt

So we just broke the Wells Fargo attempt down, let's do the same for the Capital One phishing attempt.

I have an account with Capital One, and I have seen three distinct email addresses from them: Capital One <capitalone@service.capitalone.com>, Capital One <capitalone@notification.capitalone.com>, and Capital One <capitalone@email.capitalone.com>.

I've also seen a fourth one, but the address itself is slightly disconcerting: Capital One <capitalone@capitaloneemail.com>. That's a really bad email for a bank.

We do at least see a pattern: emails from them are generally Capital One <capitalone@somedomain.capitalone.com>, which is a mostly good thing. This means we can write off Capital One <notifications.alerts@capitalone.com> as a non-legitimate email.

Next we have the same problem as the Wells Fargo email: Recipients and the .htm attachment. We'll skip those since we talked about them above.

We get to the body, and we run into a few things that are fairly alarming:

It has come to our attention that your Billing Information records are recently changed.

That's grammatically wrong, 'records have recently changed' is better.

That requires you to verify your Billing Information. Failure to validate your billing information may result to account termination.

Capital One isn't going to terminate my auto-loan over this, they would call me and verify it first. Better: 'may result to'? Bad grammer again.

To verify your billing information, Please Download Attachment and open in a browser to Continue. We value your privacy and your preferences...

Why are 'Please Download Attachment' and 'Continue' all upper-case on the first letter (capital-case)? That's not normal. Just as well: 'value your privacy and your preferences'? What does that even mean? Then the three dots / elipsis? This is atrocious.

Failure to abide by these instructions may subject you to Capital One account restrictions or inactivity.

That's not what you said above.

TM and copyright © 2017 Capital One Inc. 1 Infinite Loop, MS 96-DM, Cupertino, CA 95015.

For those who don't know, that's Apple's address.


Summary

Overall, I hope this is helpful to increase your ability (and your friends, family, coworkers and loved one's abilities) to identify phishing scams that look legitimate, and prevent becoming a victim to the tactics that these attackers use to steal your information. In a future blog post I'll talk about why it's important to identify them, and how they steal your information.

Demonstrating Insecurity of Managed Windows Program Memory

Is Memory in a Managed Windows Program Secure?

Recently I was on one of the (many) Stack Exchange sites answering a question a user posted, like usual. This question was a bit different though: the asker was concerned about the best way to make sure people couldn't read the password the user entered out of memory.

Unfortunately, this is not a task that can really be solved on consumer devices. Anyone with enough knowledge (and it's not really a lot) can do it. I'm going to demonstrate how to today with a simple Visual Studio programme.

Essentially, what I'm going to do is 'connect' to a fake SQL server (nothing about it will really exist) and then demonstrate how one can (with a copy of Visual Studio) extract the entire Connection String of that SQL connection out. It's actually quite trivial and with enough practice can be done in seconds.

Of course there are other ways to do this, it can be done programatically, there are other bits of software for it, etc. I'm just going to demonstrate how any developer can do it with the tools (s)he has at their disposal.

Creating our test projects

So the first step is to create a test project we can use to 'attack'. We're going to consider this an attacker/victim scenario, since that's what one of the real world applications is.

Our code is going to be pretty simple:

using Evbpc.Framework.Utilities.Prompting;
using System;
using System.Data.SqlClient;

namespace VictimApplication
{
    class Program
    {
        static void Main(string[] args)
        {
            var consolePrompt = new ConsolePrompt(null);

            var connectionString = new SqlConnectionStringBuilder();
            connectionString.DataSource = consolePrompt.Prompt<string>("Enter the SQL server hostname/ip", PromptOptions.Required);
            connectionString.UserID = consolePrompt.Prompt<string>("Enter the SQL server user id", PromptOptions.Required);
            connectionString.Password = consolePrompt.Prompt<string>("Enter the SQL server password", PromptOptions.Required);
            connectionString.InitialCatalog = consolePrompt.Prompt<string>("Enter the SQL server database", PromptOptions.Required);

            using (var sqlConnection = new SqlConnection(connectionString.ToString()))
            {
                try
                {
                    Console.WriteLine("Connecting...");
                    sqlConnection.Open();

                    using (var command = new SqlCommand("SELECT 15", sqlConnection))
                    {
                        Console.WriteLine($"Command output: {command.ExecuteScalar()}");
                    }
                }
                catch
                {
                    Console.WriteLine("Could not establish a connection to the server.");
                }
            }

            Console.WriteLine("Press enter to exit.");
            Console.ReadLine();
        }
    }
}

Do note this uses my ConsolePrompt from GitHub.

So we have our victim application, now we'll go ahead and attack it.

Attaching Visual Studio to a running application

You're probably expecting a title like 'attacking an application with Visual Studio' but that's not as descriptive as what we're doing. Yes, this is how you attack it, but attack sounds nefarious. We're not doing anything nefarious, we're just attaching a debugger to a running application.

So we're going to open a new instance of Visual Studio, and not open or create a project. Just open the instance.

Screenshot 1 - Fresh Visual Studio Instance

So, we've opened Visual Studio (I'm using 2015 but this should work on 2010+). The next thing we'll do is launch our application.

Screenshot 2 - Launch Application Outside Debugger

Right, so we have the application running outside the debugger. No other instances of Visual Studio need to be open, nothing else needs to be running, just that application and our fresh instance. The next step is to attach the debugger to a process.

This is under Debug -> Attach to Process. You should see a new window open, and we want to find our 'Victim Application' (VictimApplication.exe).

Screenshot 3 - Attach to Process

We'll go ahead and attach it. Our screen should change to look like we're in a regular debug session, even though we didn't launch the program through Visual Studio.

Screenshot 4 - Debug Session is Green err Blue

Now we still have our other window open with our running application in it. All we have to do next is start checking it out and see what we can inspect.

This next part isn't required, but it should help you familiarize yourself with what we're going to do. Let's hit the 'Break All' button (CTRL + ALT + Break with default shortcuts).

Screenshot 5 - Break mode

As of this moment the program is paused. Since it's a console application, you can still type into it, but your typing will not be processed by the program at this point.

Screenshot 6 - Text not handled by program

Next we'll hit 'Show Diagnostic Tools' and then select the 'Memory Usage' tab. Once we have done that, we'll hit 'Take Snapshot'.

Screenshot 7 - Taking our first memory snapshot

So now we're at the point we can start inspecting objects in our program. The first thing we'll want to do is click the blue 429 (your number may vary) link to the list of objects.

We'll then sort them by name since we're not concerned about the count, we just want to look through them.

I'm going to inspect our ConsolePrompt as an example, which in this case is listed as Evbpc.Framework.Utilities.Prompting.ConsolePrompt. When you find an object you want to inspect, hover over it and you should see an icon that looks like a square grid with a circular shape on the top-left corner, click that and a new page should open.

Screenshot 8 - Selecting an object to inspect

We'll then see a new page with all the instances of that object listed. If you hover over the Value, you should get a tool-tip that has a breakdown of the object itself, which you can explore just like normal. We'll see that the Logger is in fact null like we wanted.

Screenshot 9 - Exploring our object

Now that we've played with our explorer, we can go ahead and close that breakdown and continue with our program. We'll hit 'Continue' and resume execution. If you typed a server host into the console, you'll see as soon as we hit continue that the program continues to the next step. We'll fill out all our requirements and then break our program again when it starts connecting, and take another memory snapshot.

Screenshot 10 - Connecting to our server

We see that the new snapshot has 3,825 objects allocated, and the difference is an increase of 3,396. Our graph shows that we allocated a lot more memory (relatively speaking) and we can now go ahead and inspect our snapshot to try to find our password. We'll be looking for a string type with a value of pass.

We know it'll be part of the SqlConnection, so we'll sort that by name and then go down to SqlConnection and explore it like before.

Screenshot 11 - Find our SqlConnection

Upon exploring it we'll just a different method of extracting our string. Click 'Referenced Objects' at the bottom of our window, and hover over the middle String object. (Mine is 0x2FB0BD8)

Screenshot 12 - Extracting our Connection String

And there we have it. We have successfully extracted our password from a separate Visual Studio instance while the original application was running completely separately.

Debug Symbols and why they are important

Of course, our demonstration was made slightly easier by the inclusion of the .pdb files (debug symbols), usually you won't have access to these for the running application, so you'll have to look a little harder sometimes to find what you're looking for.

If you don't know what Debug Symbols are, Wikipedia has a nice description. Essentially, the pdb file (stands for 'Program Database') is the symbol map for .NET programs. It contains each generated instruction header and what the generated name of it was.

Finding our String without SqlConnection

The last thing we'll do is find our string value without exploring the SqlConnection object. We're only going to look with the Diff list, and run from there.

So, we'll restart our application, then attach the debugger, then enter our host and user, then take a memory snapshot like we did earlier.

Screenshot 13 - Round 2 First Snapshot

Then we'll hit 'Continue', enter our password, and take another snapshot.

Screenshot 14 - Round 2 Second Snapshot

The next step is to disable 'Just My Code' in the filter. If we don't do this it becomes much more difficult to locate what we changed.

Screenshot 15 - Round 2 Disable Just My Code

So we see that it created one string, by the Count Diff. being +1 on the String type, this helps us narrow down what we're looking for. If click once into it, and view our 'Paths to Root', it helps us discover that we have +1 in String [Local Variable]. So we're in the right place.

Screenshot 16 - Round 2 String Local Variable

We'll inspect the String like before (Square icon with Round outset) and we'll see that by default it sorts the list by `'Inclusive Size (Bytes)', we'll sort it by 'Instance'. Theorhetically our password should be the last instance listed. If we scroll to the bottom of the list we see that, indeed, it is.

We also see that our user id is right above it.

Screenshot 17 - Round 2 Find our Password


And there we have it! We learned how to inspect objects in our program when it was launched outside Visual Studio by attaching a debug instance of Visual Studio to it.