Is a NetNTLMv1 hash reversible?

No. NetNTLMv1 is a one-way hash; you cannot reverse it. You can only guess inputs and compare, which is what hashcat and John do.

What is the hashcat mode for NetNTLMv1?

Use `-m 5500` to tell hashcat to treat the input as NetNTLMv1.

How long does it take to crack NetNTLMv1?

NetNTLMv1 is fast to compute, so weak passwords often fall in seconds to minutes on a GPU; strong, long passwords remain infeasible.

Is a NetNTLMv1 hash reversible?

No. NetNTLMv1 is a one-way hash; you cannot reverse it. You can only guess inputs and compare, which is what hashcat and John do.

What is the hashcat mode for NetNTLMv1?

Use `-m 5500` to tell hashcat to treat the input as NetNTLMv1.

How long does it take to crack NetNTLMv1?

NetNTLMv1 is fast to compute, so weak passwords often fall in seconds to minutes on a GPU; strong, long passwords remain infeasible.

How to identify and crack a NetNTLMv1 hash

NetNTLMv1 is a network authentication 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 NetNTLMv1 entirely in your browser — your hash is never uploaded. A typical example looks like this:

u::N46iSNekpT:c8a8c69e96c0e57a07a5b3b0b97e2e69cca39db9c47e5b2a:c8a8c69e96c0e57a07a5b3b0b97e2e69cca39db9c47e5b2a:1122334455667788

Cracking NetNTLMv1 with hashcat

Save the hash to a file and run hashcat in mode -m 5500. Start with a wordlist such as rockyou.txt:

echo 'u::N46iSNekpT:c8a8c69e96c0e57a07a5b3b0b97e2e69cca39db9c47e5b2a:c8a8c69e96c0e57a07a5b3b0b97e2e69cca39db9c47e5b2a:1122334455667788' > hash.txt && hashcat -m 5500 hash.txt /usr/share/wordlists/rockyou.txt

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

echo 'u::N46iSNekpT:c8a8c69e96c0e57a07a5b3b0b97e2e69cca39db9c47e5b2a:c8a8c69e96c0e57a07a5b3b0b97e2e69cca39db9c47e5b2a:1122334455667788' > hash.txt && hashcat -m 5500 hash.txt /usr/share/wordlists/rockyou.txt -r /usr/share/hashcat/rules/best64.rule

Cracking NetNTLMv1 with John the Ripper

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

echo 'u::N46iSNekpT:c8a8c69e96c0e57a07a5b3b0b97e2e69cca39db9c47e5b2a:c8a8c69e96c0e57a07a5b3b0b97e2e69cca39db9c47e5b2a:1122334455667788' > hash.txt && john --format=netntlm --wordlist=/usr/share/wordlists/rockyou.txt hash.txt