Executable Atomic Red Team test cases for exercising this technique in a lab. Copy a command, run it on the listed platform, confirm your detections fire.
command_promptwindowsDeobfuscate/Decode Files Or Information
Encode/Decode executable
Upon execution a file named T1140_calc_decoded.exe will be placed in the temp folder
certutil -encode #{executable} %temp%\T1140_calc.txt
certutil -decode %temp%\T1140_calc.txt %temp%\T1140_calc_decoded.exe
command_promptwindowsCertutil Rename and Decode
Rename certutil and decode a file. This is in reference to latest research by FireEye [here](https://www.fireeye.com/blog/threat-research/2018/09/apt10-targeting-japanese-corporations-using-updated-ttps.html)
copy %windir%\system32\certutil.exe %temp%\tcm.tmp
%temp%\tcm.tmp -encode #{executable} %temp%\T1140_calc2.txt
%temp%\tcm.tmp -decode %temp%\T1140_calc2.txt %temp%\T1140_calc2_decoded.exe
shlinux, macosBase64 decoding with Python
Use Python to decode a base64-encoded text string and echo it to the console
ENCODED=$(python3 -c 'import base64;enc=base64.b64encode("#{message}".encode());print(enc.decode())')
python3 -c "import base64;dec=base64.b64decode(\"$ENCODED\");print(dec.decode())"
python3 -c "import base64 as d;dec=d.b64decode(\"$ENCODED\");print(dec.decode())"
python3 -c "from base64 import b64decode;dec=b64decode(\"$ENCODED\");print(dec.decode())"
python3 -c "from base64 import b64decode as d;dec=d(\"$ENCODED\");print(dec.decode())"
echo $ENCODED | python3 -c "import base64,sys;dec=base64.b64decode(sys.stdin.read());print(dec.decode())"
echo $ENCODED > #{encoded_file} && python3 -c "import base64;dec=base64.b64decode(open('#{encoded_file}').read());print(dec.decode())"
shlinux, macosBase64 decoding with Perl
Use Perl to decode a base64-encoded text string and echo it to the console
ENCODED=$(perl -e "use MIME::Base64;print(encode_base64('#{message}'));")
perl -le "use MIME::Base64;print(decode_base64('$ENCODED'));"
echo $ENCODED | perl -le 'use MIME::Base64;print(decode_base64(<STDIN>));'
echo $ENCODED > #{encoded_file} && perl -le 'use MIME::Base64;open($f,"<","#{encoded_file}");print(decode_base64(<$f>));'
shlinux, macosBase64 decoding with shell utilities
Use common shell utilities to decode a base64-encoded text string and echo it to the console
ENCODED=$(echo '#{message}' | base64)
printf $ENCODED | base64 -d
echo $ENCODED | base64 -d
echo $(echo $ENCODED) | base64 -d
echo $ENCODED > #{encoded_file} && base64 -d #{encoded_file}
echo $ENCODED > #{encoded_file} && base64 -d < #{encoded_file}
echo $ENCODED > #{encoded_file} && cat #{encoded_file} | base64 -d
echo $ENCODED > #{encoded_file} && cat < #{encoded_file} | base64 -d
bash -c "{echo,\"$(echo $ENCODED)\"}|{base64,-d}"
shlinuxBase64 decoding with shell utilities (freebsd)
Use common shell utilities to decode a base64-encoded text string and echo it to the console
ENCODED=$(echo '#{message}' | b64encode -r -)
printf $ENCODED | b64decode -r
echo $ENCODED | b64decode -r
echo $(echo $ENCODED) | b64decode -r
echo $ENCODED > #{encoded_file} && b64encode -r #{encoded_file}
echo $ENCODED > #{encoded_file} && b64decode -r < #{encoded_file}
echo $ENCODED > #{encoded_file} && cat #{encoded_file} | b64decode -r
echo $ENCODED > #{encoded_file} && cat < #{encoded_file} | b64decode -r
shlinuxFreeBSD b64encode Shebang in CLI
Using b64decode shell scripts that have Shebang in them. This is commonly how attackers obfuscate passing and executing a shell script. Seen [here](https://www.trendmicro.com/pl_pl/research/20/i/the-evolution-of-malicious-shell-scripts.html) by TrendMicro, as well as [LinPEAS](https://github.com/carlospolop/PEASS-ng/tree/master/linPEAS). Also a there is a great Sigma rule [here](https://github.com/SigmaHQ/sigma/blob/master/rules/linux/process_creation/proc_creation_lnx_base64_shebang_cli.yml) for it.
echo #{bash_encoded} | b64decode -r | sh
echo #{dash_encoded} | b64decode -r | sh
echo #{fish_encoded} | b64decode -r | sh
echo #{sh_encoded} | b64decode -r | sh
shlinux, macosHex decoding with shell utilities
Use common shell utilities to decode a hex-encoded text string and echo it to the console
ENCODED=$(echo '#{message}' | xxd -ps -c 256)
printf $ENCODED | xxd -r -p
echo $ENCODED | xxd -r -p
echo $(echo $ENCODED) | xxd -r -p
echo $ENCODED > #{encoded_file} && xxd -r -p #{encoded_file}
echo $ENCODED > #{encoded_file} && xxd -r -p < #{encoded_file}
echo $ENCODED > #{encoded_file} && cat #{encoded_file} | xxd -r -p
echo $ENCODED > #{encoded_file} && cat < #{encoded_file} | xxd -r -p
shlinux, macosLinux Base64 Encoded Shebang in CLI
Using Linux Base64 Encoded shell scripts that have Shebang in them. This is commonly how attackers obfuscate passing and executing a shell script. Seen [here](https://www.trendmicro.com/pl_pl/research/20/i/the-evolution-of-malicious-shell-scripts.html) by TrendMicro, as well as [LinPEAS](https://github.com/carlospolop/PEASS-ng/tree/master/linPEAS). Also a there is a great Sigma rule [here](https://github.com/SigmaHQ/sigma/blob/master/rules/linux/process_creation/proc_creation_lnx_base64_shebang_cli.yml) for it.
echo #{bash_encoded} | base64 -d | bash
echo #{dash_encoded} | base64 -d | bash
echo #{fish_encoded} | base64 -d | bash
echo #{sh_encoded} | base64 -d | bash
bashlinux, macosXOR decoding and command execution using Python
An adversary can obfuscate malicious commands or payloads using XOR and execute them on the victim's machine. This test uses Python to decode and execute commands on the machine.
python3 -c 'import base64; import subprocess; xor_decrypt = lambda text, key: "".join([chr(c ^ ord(k)) for c, k in zip(base64.b64decode(text.encode()), key)]); command = "#{encrypted_command}"; key = "#{xor_key}"; exec = xor_decrypt(command, key); subprocess.call(exec, shell=True)'
command_promptwindowsExpand CAB with expand.exe
Uses expand.exe to extract a file from a CAB created locally. This simulates adversarial use of expand on cabinet archives.
Upon success, art-expand-source.txt is extracted next to the CAB.
mkdir "#{output_dir}" >nul 2>&1
echo hello from atomic red team > "PathToAtomicsFolder\T1140\src\art-expand-source.txt"
makecab "PathToAtomicsFolder\T1140\src\art-expand-source.txt" "#{cab_path}"
pushd "#{output_dir}"
expand "#{cab_path}" -F:* .
popd