GEN:SID 1:974
Message WEB-IIS Directory transversal attempt
Summary This event is generated when an attempt is made to peform a denial of service against Internet Information Service (IIS) 1.0 hosts.
Impact Denial of service.  This attack may cause an IIS 1.0 server to crash.
Detailed Information IIS 1.0 servers are vulnerable to a denial of service attack when a malformed request containing "..\.." is sent to the server.  The service must be restarted to restore functionality.
Affected Systems IIS 1.0 Servers
Attack Scenarios An attacker can send a malformed request to a vulnerable IIS server to cause a denial of service.
Ease of Attack Simple.  Send a request similar to this:  GET ..\..
Corrective Action Upgrade to a more current version of IIS.
Additional References CVE
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-1999-0229

Bugtraq:
http://www.securityfocus.com/bid/2218
Rule References bugtraq: 2218
cve: 1999-0229