🛠️ Obfuscation
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Theory
Obfuscation is a way to hide a shellcode. generally symmetric algorithms are used
Practice
Manual obfuscation
Below is a list of ways that allow you to go under the radar of anti-virus software, so put all the chances on your side and use several techniques.
You should also change the logo of the binary as well as its description and its creation date (sandboxes check that the binary is not too recent).
Shellcode encoding
For this part the principle is simple: camouflaged its active load, to do this you will need to code a function to encode, but also to decode, free to choose algorithm this technique works particularly well for static bypass.
Here is a link that will allow you to understand and write your first program:
Indirect syscall
the principle of this method is to call directly the memory addresses instead of using the API functions an article which explains things very well is this one.
Delayed execution
In order to compromise the machine discreetly, sleeps are also used a lot, There are several methods: WaitForSingleObjectEx, Foliage, Ekko, Deathsleep.
A good part of them are very well explained at the following address : https://evasions.checkpoint.com/techniques/timing.html#delayed-execution
Disable ETW
There are several ways to disable logging, either via nt!EtwpStopTrace, or advapi32!EventWrite but also ntdll!ETWEventWrite.
To better understand these keywords, I invite you to read this article: https://www.binarly.io/posts/Design_issues_of_modern_EDRs_bypassing_ETW-based_solutions/index.html.
Another great resource : https://www.mdsec.co.uk/2020/03/hiding-your-net-etw/.
Automatic obfuscation
Depending on your needs, you can use tools available for the most part on github, they are sorted by category below.
ℹ️ You can also find all the tools in the mindmap section.
Packing
- https://github.com/phra/PEzor
- https://github.com/klezVirus/inceptor
- https://github.com/govolution/avet
- https://github.com/Nariod/RustPacker
- https://github.com/DavidBuchanan314/monomorph
- https://github.com/upx/upx
## Office macro
- https://github.com/sevagas/macro_pack
- https://github.com/optiv/IvyAMSI Bypass
- https://github.com/CCob/SharpBlock
- https://github.com/danielbohannon/Invoke-Obfuscation
- https://github.com/klezVirus/Chameleon
- https://github.com/tokyoneon/ChimeraEntropy
https://github.com/kleiton0x00/Shelltropy
LOLBIN
RemComSvc - https://gist.github.com/snovvcrash/123945e8f06c7182769846265637fedbSignature hiding
- https://github.com/optiv/ScareCrow
- https://github.com/paranoidninja/CarbonCopy