Anti-virus firms are warning of the appearance of fresh variants of the Blaster worm, the first version of which created chaos by crashing numerous vulnerable Windows machines earlier this week.
According to an analysis by Kaspersky Labs on Blaster-C, slight changes have been applied to the appearance of the worm such as a new name of the main worm-carrier file (TEEKIDS.EXE instead of MSBLAST.EXE), a new method of the code compression (FSG instead of UPX), and new "copyright" strings in the body of the worm abusing Microsoft and anti-virus developers. Similar types of changes have been applied to Blaster-B (eg. PENIS32.EXE instead of MSBLAST.EXE etc.)
The worm code essentially remains the same in the copycats as in the original. For this reason most AV scanners will spot the new variants without additional updates.
Vincent Weafer, Senior Director at Symantec Security Response Centre, said it seeing very little extra activity as a result of either Blaster-B or Blaster-C, which he described as "very minor 'renamed and repacked' variants" of the original Blaster worm. However he urged caution because additional variants of the worm, some of which may prove to be even more potent than the original worm, can be expected. ®