Security 3 - Malware

< CS101

Pre-Malware Category: Social Engineering Attacks

"Social engineering" means using human to human contact, say on the phone, to get into a system. Some people can be quite persuasive on the phone, and most people are polite and helpful by default (see, we're not such a bad species!). A bad guy might pose as technician showing up, trying to fix the printer. People will often be polite to a well dressed person on site who appears to be doing something proper. An example from a few years ago was leaving USB keys in the parking lot containing malware, counting on the curiosity of those picking them up and taking them inside and plug them in to their machines. Windows has (had?) an extremely insecure "autorun" feature where it will automatically run certain code on an inserted drive. On a properly designed operating system, plugging in a flash drive lets you look at its contents, not start trusting and running the bytes found there.

Malware Attacks

This is a big category, where the bad guy tricks the victim into running bad software ("malware") on the victim's computer. I'm lumping viruses, worms, and trojans all into this category.

How Do I Feel About This File?

Passive Content = Safe, Program = Unsafe

The last, .exe case is the main risk here, although all of the above scenarios could result in problems. If code written by the bad guy, a .exe, runs on your computer, the bad guy now in essence has control and access to the data on your computer.

Suppose the bad guy is sitting at the keyboard of your unlocked computer, obviously they can do whatever they want with your data. The .exe case is very similar -- the code in the .exe could do what the bad guy wants -- look for a particular file, email it off the machine, etc. Most of the "attacks" listed below in essence try to re-create the .exe case, and the defenses center on preventing the .exe case.

"Malware" is the general term for a program written by the bad guy to do bad things to your machine - break in to the machine, steal passwords, send spam, etc.

Bad Guy Malware .EXE Techniques

Malware 1 - Trojan

Here is the Mac OS X warning that you are double clicking something that is a program to run...
operating system warns that a file is a program when double clicked

A "trojan" is a malware disguised as something else, like "awesome-cursors.exe" or "fun-game.exe" or "JustinBeiber.JPEG.exe" (Windows is vulnerable to extensions other than .exe, it's just used for the examples here). The term refers to the Trojan Horse story from antiquity. If the user can be tricked into double clicking the trojan, running it, then the bad guys have won. The https is no defense.

Malware Example - Keylogger

Malware 2 - Vulnerability

Suppose there is an engineering flaw in Firefox or the Flash player or some other software on your machine, such that if it sees a particular sequence of bytes as input, there is bug that allows a takeover of the machine. This is called a "vulnerability", and it is one of the scary cases. If the user browses over to a web site this is hosting the "attack" content and their browser is vulnerable, then the bad guy can get it just from that. The bad guy can make the web site appear attractive, post links on reddit or whatever to try to drive traffic to the site. This attack is scary because it does not require the user to do anything especially foolish.

Such vulnerabilities in Flash and IE used to be quite common. However, the engineering culture seems to be catching up, and this case is becoming more rare. The most important step is being sure to run the most up to date, current version of your browser and any plugins such as Flash. Firefox et al have switched to make programs auto-check for new versions, so the user does not need to do much to have the most recent version. Often a vulnerability is fixed, and months later attackers start using it on sites, but they can still succeed with users using old versions.

Zero-Day Vulnerability

Malware Example: Zombie Botnets

In parallel with other harm, the malware may set up the compromised machine as a "zombie" or "bot". A zombie is a machine, one of thousands, which all together form a "botnet". The owner of the botnet can distribute tasks to be done by all the zombies, like this: "ok everyone, here is a list of 10 million email addresses, start sending spam email to them." Because the number of zombies is large, the botnet can accomplish things that require a lot of machines. Sending spam is a great example. Another great example is doing dictionary-password attacks on random websites, as shown previously.

Malware Example - Encryption "Ransomware"

WanaCry Ransomware Example - last week!

Malware Example - DDOS Attack

The zombies can also be used to "attack" a web site, by all trying to access it at the same time. With some tends of thousands of machines all hitting a site at the same time, it is possible to in effect make the site unavailable to the internet. This is called a "denial of service" (DOS) attack. It's not breaking into the site or stealing passwords or money; instead it's making the proper function of something unavailable.

Obviously the botnet is not paying the owner of the machine. The botnet is stealing the use of the machine from its proper owner. If a machine seems sluggish in regular use, and the networking lights are blinking like mad all the time... the machine may be a zombie. Like a parasite in the real world, the zombie software wants the machine to still mostly work for its owner, otherwise they would be motivated to clean it.

One problem with zombies is that the owners may not be all that motivated to fix it. The millions of compromised Windows machines out there are putting out this pollution that causes problems for us all. If you think a machine is a zombie, you should erase it and fix it. The zombie may be doing who knows what with your passwords, your data, there's too many risks.

In what would make a most interesting Business School case study, there are active markets in botnets. The botnet owners basically rent out their botnets for spamming or whatever use a bad guys wants to pay for that day.

Interesting Attack Example - CEO Payment Email Scam