How to identify and crack an LM (LAN Manager) hash

LM (LAN Manager) is an windows credential hash type. It is fast and typically unsalted, which makes weak passwords recoverable quickly on consumer GPU hardware. This page shows how to recognise it and the exact commands to attack it.

All identification runs locally in WebAssembly. The commands below write the hash to a local file on your machine — nothing is sent to this site.

Identifying the hash

The hash identifier on the home page detects LM (LAN Manager) entirely in your browser — your hash is never uploaded. A typical example looks like this:

299bd128c1101fd6299bd128c1101fd6

Cracking LM (LAN Manager) with hashcat

Save the hash to a file and run hashcat in mode -m 3000. Start with a wordlist such as rockyou.txt:

echo '299bd128c1101fd6299bd128c1101fd6' > hash.txt && hashcat -m 3000 hash.txt /usr/share/wordlists/rockyou.txt

Add a rule set to mutate dictionary words (capitalisation, leetspeak, appended digits) and dramatically widen coverage:

echo '299bd128c1101fd6299bd128c1101fd6' > hash.txt && hashcat -m 3000 hash.txt /usr/share/wordlists/rockyou.txt -r /usr/share/hashcat/rules/best64.rule

Cracking LM (LAN Manager) with John the Ripper

John the Ripper can attack the same hash with the lm format:

echo '299bd128c1101fd6299bd128c1101fd6' > hash.txt && john --format=lm --wordlist=/usr/share/wordlists/rockyou.txt hash.txt