This attack could pose a moderate security threat. It does not require immediate action.
This signature detects an attempt to crash a Microsoft IIS server by sending a malformed PROPFIND request followed by a larger buffer.
WebDAV is an extension of the HTTP protocol and by default installs on Microsoft IIS 5.0. WebDav enables remote users to manage and collaboratively edit files on remote web servers.
Microsoft IIS is subject to a denial of service attack. Because WebDAV contains a flaw in the handling of certain malformed requests, an attacker submitting multiple malformed WebDAV 'PROPFIND' requests could cause the server to stop responding, leaving the server unable to accept any new HTTP sessions.
The duration of the denial of service is dependant on the amount of time an attacker would continuously send the request. Once the malformed requests come to an end, the server will regain normal functionality.
This vulnerability has also been known to restart the IIS services.