This attack could pose a serious security threat. You should take immediate action to stop any damage or prevent further damage from happening.
This signature detects a maliciously crafted ASF file attempting to exploit a vulnerability that may allow Remote Code Execution when the file is processed by Windows Media Player.
A vulnerability exists in Windows Media Player 6.4 which could lead to file data being written past the end of a heap buffer, leading to arbitrary code execution, while parsing ASF files. WMA and WMV are examples of ASF files. This vulnerability can be triggered when browsing to a folder containing a malformed ASF file using Windows Explorer.