Troj/JpegBld-A is a kit that can be used to generate Jpeg image files in order to exploit the vulnerability in Microsoft gdiplus.dll library as described in Microsoft Security Bulletin MS04-028.
The user may specify a URL that will be used for the construction of the exploit. Once the exploit is triggered the executable code embedded in the image file will attempt to download and run a file specified as the input to the Trojan. The images produced by this generator are detected by Sophos Anti-Virus as Exp/MS04-028.