When you submit b4b9b02e6f09a9bd760f388b67251e2e , they check their database. If a previous user or their own rainbow tables mapped that hash to Password123 , they return it.
The NTLM hash is generated by taking a user's password and processing it through the . Because this protocol is legacy and lacks modern cryptographic safeguards like "salting," it is highly vulnerable to rapid recovery using specialized tools. Core Concepts for Development ntlm-hash-decrypter
The decrypter tries every possible combination of characters. While guaranteed to work eventually, this is computationally expensive and can take years for complex passwords. 3. Rainbow Tables When you submit b4b9b02e6f09a9bd760f388b67251e2e