Part 2 - Packing a RAT with UPX/Packers

Typically after a malware developer has created his malicious payload (for example using the steps mentioned in the post about generating a RAT with MSFVenom) they test whether that malicious program can be detected by antivirus software.

Enter Virustotal. This is a website that can be used for both positive and negative means (as is the case with all forms of education). With Virustotal, bad actors can use it to test their payloads to see if it can be detected by antivirus software that is the most popular on the market. Regular actors/uses can use it to check if a tool or software they want to run on their computer is malicious or not.

How to do this is also illustrated in the video below. In most cases malware analysts use it for static analysis of potentially malicious programs.

So typically there are a number of ways that antivirus software works but the one method that bad actors try to combat in this scenario is signature based analysis. By this, a hash is generated for each and every program that is scanned by antivirus software and then blacklists are generated from this. The blacklist is comprised of programs that are seen to be malicious. This hash is the signature of the malicious program.

So whenever we upload a program to Virustotal, the signature is generated and compared to the database of blacklisted malicious programs from a multitude of antivirus software.

Packing/Executable Compression/ Obfuscation is one way of avoiding this. In the most lay of layman terms, its basically sticking the malware in a shell and then passing that shell to the antivirus. The antivirus generates a hash of the shell and this is nothing like the signature of the malware contained within the shell and in most cases, a false-negative is the result. There are open-source packers like UPX and then there are others that are proprietary.

This demo shows how to pack and unpack a program using UPX.

This video tutorial is for educational purposes only.

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Part 4 - Static and Dynamic analysis of a Remote Access Trojan

Now we delve into the world of Malware analysis, This can be either Basic static, basic dynamic, advanced static or advanced dynamic malware analysis. By static we just mean we do not execute the malicious program but simply analyse it by looking at the headers, the linked libraries it calls, its resources, etc. When it is advanced, this would mean breaking it down and analysing it with tools such as IDA Pro. Dynamic means we run it in a safe environment and see what it does. Basic tools include Regshot which simply takes a snapshot of the registry before and after the malware was executed. It then returns only the changes made in between those two points in time. Advanced would involve the use of a sandbox that monitors all the calls the malware makes as well as the connection attempts it tries to make to outside terminals or C&C servers. The video below illustrates Basic Static and Dynamic malware analysis.

Password Cracking: RainbowCrack table generation, sorting and usage

I had to do this demo after one of my students asked for my assistance regarding how to use this tool. Usually, I just assign different tools to them individually depending on the aspect of penetration testing we are covering (session hijacking, vulnerability scanning, etc) and then tell them to submit a report and a video demo of how the tool is used. Anyway, after a brief one-to-one discussion I realized the student had actually done the research on how rainbow tables operate (above and beyond the material in the lecture slides) so I figured that if he was here asking for assistance, he genuinely needed it. The tool is available at the RainbowCrack site. A detailed description of this nifty tool can also be found here . So, firstly I had to generate the rainbow tables. The command line syntax is: rtgen hash_algorithm charset plaintext_len_min plaintext_len_max table_index chain_len chain_num part_index where: hash_algorithm Rainbow table is hash algorithm sp...

Forensics: Recovery of Files Ep 2 - Data Rescue PC3

This is the second episode in the Recovery of Files series. Episode 1 has a little more background on the whole aspect of file recovery. The video below shows a demo of how to recover lost/deleted files using the proprietary tool commonly known as Data Rescue PC3 . As in episode 1, in the video, we format the USB drive, add stuff to it, and then format it again in order to recover the deleted files. Again, just like in episode 1, you will also note that not only the files we lost upon formatting are the ones that are recovered, but this will also include the files from previous drive formats too.

Robsec

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