Of all the known computer worms, Mytob was the most resilient and busy. For several months last year, there was at least one new Mytob variant discovered in a month. (See this Techweb article dated April 11, 2005.)

Trend Micro reports two new variants of this worm: WORM_MYTOB.KJ and WORM_MYTOB.JP. And today, I had received a total of 11 emails (all within an hour) containing an attached copy of WORM_MYTOB.FC. MYTOB.FC is an old variant already, discovered last May 2005.

Users are advised to update their anti-virus applications and be careful in handling email messages (specially with executable and/or double-extension files) coming from unknown sources (and even from known sources). BTW, Thunderbird usually tags Mytob emails as junk/spam, so that’s another added protection for users.