Python Obfuscation for Dummies

Published: 2022-10-18
Last Updated: 2022-10-18 05:11:17 UTC
by Xavier Mertens (Version: 1)
2 comment(s)

Recently, I found several malicious Python scripts that looked the same. They all contained the same strings at the end:


Pretty nifty obfuscation technique because you cannot get any idea of the script's purpose without executing it in a sandbox or checking deeper. Obfuscation is a crucial element for attackers because they help to bypass classic security controls and they slow down the analysis process by Security Analysts. How does it work? Attackers write their code then they use tools to obfuscate the code. Of course, they are tools available in the underground, but there are also tools publicly available.

One of them is called[1], which provides a free online Python obfuscation tool:

Here is a simple/fantastic script:

print "Hello world!"

The obfuscated code is:

import base64, codecs
magic = 'IyEvdXNyL2Jpb'
love = 'v9jrKEbo24XpU'
god = 'JpbnQgIkhlbGx'
destiny = 'iVUqipzkxVFVX'
joy = '\x72\x6f\x74\x31\x33'
trust = eval('\x6d\x61\x67\x69\x63') + eval('\x63\x6f\x64\x65\x63\x73\x2e\x64\x65\x63\x6f\x64\x65\x28\x6c\x6f\x76\x65\x2c\x20\x6a\x6f\x79\x29') + \
eval('\x67\x6f\x64') + eval('\x63\x6f\x64\x65\x63\x73\x2e\x64\x65\x63\x6f\x64\x65\x28\x64\x65\x73\x74\x69\x6e\x79\x2c\x20\x6a\x6f\x79\x29')

But is the obfuscation efficient to make the Python script bypass some AV's? I selected a classic script (a password stealer). The script has a current score of 4/60 on VT (SHA256:5f9a62e6c09f085ffb60caefbe155e3ead38848d0f5201517ca0c3cccc09ce78)[2]. The obfuscated script received a score of 5/60.

Another one (a keylogger) with a score of 10/59 (SHA256:77d1cda4ab39e3e0f0a7af4c3d86a42721b9a0d62ccf2f3112988e518c296af5)[3]. The obfuscated version also received a score of 5/60.

As you can see, if the code is really difficult to understand out-of-the-box by an Analyst (goal completed) without proper tools. However, this obfuscation tool does not always improve the detection rate of antivirus tools.


Xavier Mertens (@xme)
Senior ISC Handler - Freelance Cyber Security Consultant

2 comment(s)


Interestingly, knowing nothing of Python that did not take long to boil down to just needing to do a base64 decode
of the value IyEvdXNyL2Jpbi9weXRob24KcHJpbnQgIkhlbGxvIHdvcmxkISIK and no Python interpreter needed.

I am surprised it was not doing anything other than rot13 and base64, not even Unicode or EBCDIC.
I know a decent bit about Python, but I do agree with you and I made an account because this is the perfect opportunity to share a tool I use quite a bit. Keep in mind this is not specifically for you necessarily, but just anybody that comes across this post. If you use and just copy-paste in each section of the obfuscated python code using the "magic" setting you can fully understand the obfuscated code without even understanding Python.

I am in no way affiliated with cyberchef I just think it's a great tool hope this helps some other people. Cheers.,false,false,'')

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