Sobig

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The Sobig Worm was a computer worm that infected millions of Internet-connected, Microsoft Windows computers in August 2003.^[1]

Although there were indications that tests of the worm were carried out as early as August 2002, Sobig.A was first found in the wild in January 2003. Sobig.B was released on May 18, 2003. It was first called Palyh, but was later renamed to Sobig.B after anti-virus experts discovered it was a new generation of Sobig. Sobig.C was released May 31 and fixed the timing bug in Sobig.B. Sobig.D came a couple of weeks later followed by Sobig.E on June 25. On August 19, Sobig.F became known and set a record in sheer volume of e-mails.

The worm was most widespread in its "Sobig.F" variant.

As of 2018^[update], Sobig is the second fastest computer worm to have ever entered the wild, being surpassed only by Mydoom.

Sobig was not only a computer worm in the sense that it replicates by itself, but also a Trojan horse in that it masquerades as something other than malware. The Sobig.F worm would appear as an electronic mail with one of the following subjects:

• Re: Approved
• Re: Details
• Re: Re: My details
• Re: Thank you!
• Re: That movie
• Re: Wicked screensaver
• Re: Your application
• Thank you!
• Your details

It would contain the text: "See the attached file for details" or "Please see the attached file for details", as well as an attachment as one of the following names:

• application.pif
• details.pif
• document_9446.pif
• document_all.pif
• movie0045.pif
• thank_you.pif
• your_details.pif
• your_document.pif
• wicked_scr.scr