W32/Mytob-AJ is a mass-mailing worm and backdoor Trojan that targets users of Internet Relay Chat programs. W32/Mytob-AJ is capable of spreading through various operating system vulnerabilities such as LSASS (MS04-011).

The worm also prevents access to anti-virus and security-related websites. W32/Mytob-AJ harvests email addresses from files found on the infected computer and from the Windows address book.

The following patches for the operating system vulnerabilities exploited by W32/Mytob-AJ can be obtained from this Microsoft website.