In case that doesn’t work, there was an “Open” command added to the context menu. The AutoRun commands specify that the autorun.inf file itself to be executed, which in turn executes the worm’s code, he explained. When Windows parses the autorun.inf file all of the MZ content will be ignored as garbage until the legitimate AutoRun commands that are appended at the end of the file are encountered.” Stuxnet uses this fact to its advantage by placing the MZ file first within the autorun.inf file. “Specifically, any characters that are not understood as being part of legitimate AutoRun commands are skipped as garbage and parsing continues. “When Windows parses autorun.inf files the parsing is quite forgiving,” he continued. “The specially crafted file could be interpreted as either an executable file or as a correctly-formatted autorun.inf file.

“The worm’s trick was to create an autorun.inf file in the root of removable drives that served two different purposes,” blogged O Murchu, manager of operations for Symantec Security Response. Instead, the malware abused Windows’ AutoRun feature to compromise machines through infected USB devices. 24 as security researchers continue to peel back the layers of the complex malware.Īccording to Symantec researcher Liam O Murchu, early versions of Stuxnet were targeting industrial control systems without the help of a vulnerability at all.

More details about the Stuxnet worm trickled out Sept.

Autorun malware