log4j RCE Exploitation Detection

You can use these commands and rules to search for exploitation attempts against log4j RCE vulnerability CVE-2021-44228

Grep / Zgrep

This command searches for exploitation attempts in uncompressed files in folder /var/log and all sub folders

sudo egrep -I -i -r '\$(\{|%7B)jndi:(ldap[s]?|rmi|dns|nis|iiop|corba|nds|http):/[^\n]+' /var/log

This command searches for exploitation attempts in compressed files in folder /var/log and all sub folders

sudo find /var/log -name \*.gz -print0 | xargs -0 zgrep -E -i '\$(\{|%7B)jndi:(ldap[s]?|rmi|dns|nis|iiop|corba|nds|http):/[^\n]+'

Grep / Zgrep — Obfuscated Variants

These commands cover even the obfuscated variants but lack the file name in a match.

This command searches for exploitation attempts in uncompressed files in folder /var/log and all sub folders

sudo find /var/log/ -type f -exec sh -c "cat {} | sed -e 's/\${lower://'g | tr -d '}' | egrep -I -i 'jndi:(ldap[s]?|rmi|dns|nis|iiop|corba|nds|http):'" \;

This command searches for exploitation attempts in compressed files in folder /var/log and all sub folders

sudo find /var/log/ -name '*.gz' -type f -exec sh -c "zcat {} | sed -e 's/\${lower://'g | tr -d '}' | egrep -i 'jndi:(ldap[s]?|rmi|dns|nis|iiop|corba|nds|http):'" \;

Log4Shell-Rex

A massive regex to cover even the most obfuscated variants: https://github.com/back2root/log4shell-rex

Log4Shell Detector (Python)

Python based scanner to detect the most obfuscated forms of the exploit codes.

https://github.com/Neo23x0/log4shell-detector

Find Log4j on Linux

ps aux | egrep '[l]og4j'
find / -iname "log4j*"
lsof | grep log4j
grep -r --include *.[wj]ar "JndiLookup.class" / 2>&1 | grep matches

Find Vulnerable Log4j on Windows

gci 'C:\' -rec -force -include *.jar -ea 0 | foreach {select-string "JndiLookup.class" $_} | select -exp Path

by @CyberRaiju

by @Neo23x0