Worm:W32/Downadupjob.gen!A is a Generic Detection for .JOB files used by Worm:W32/Downadup.
The .JOB file used by the worm is detected as it is part of the worm's propagation routine. Downadup attempts to spread itself using Windows Scheduled Tasks. The .JOB file defines a scheduled task, which in Downadup's case triggers an execution of the worm library via rundll32.exe. Legitimate tasks are usually located in the following folder:
For more about Downadup variants and activities, see:
About Generic Detections
Unlike more traditional detections (also known as signatures or single-file detections) a Generic Detection does not identify a unique or individual malicious program. Instead, a Generic Detection looks for broadly applicable code or behavior characteristics that indicate a file as potentially malicious, so that a single Generic Detection can efficiently identify dozens, or even hundreds of malware.
For more information, see the Generic Detection description.