Exp/Phel-A detects files that exploit the HTML Help Control Vulnerability which affects systems installed with the following Microsoft operating systems:
Windows 2000 Service packs 3 and 4.
Windows XP Service packs 1 and 2.
Windows XP 64-bit Edition Service pack 1.
Windows XP 64-bit Edition Version 2003.
Windows Server 2003.
Windows Server 64-bit Edition.
Windows 98/SE/ME.
This vulnerability allows arbitrary code execution on the vulnerable system by bypassing security constraints established by the operating system.
For more information please refer to Microsoft Security Bulletin MS05-001.