Buffer overflow vulnerability in the WebDAV service of Microsoft IIS CVE-2017-7269

April 11, 2017

Web Distributed Authoring and Versioning (WebDAV) is an extension of the Hypertext Transfer Protocol (HTTP) that allows clients to perform remote Web content authoring operations.
The WebDAV protocol provides a framework for users to create, change and move documents on a server, typically a web server or web share.

Buffer overflow exists in the ScStoragePathFromUrl function in the WebDAV service of Internet Information Services (IIS) 6.0 in Microsoft Windows Server 2003 R2.This allows remote attackers
to execute arbitrary code via a long header beginning with "If:

The WebDAV PROPFIND Method retrieves properties for a resource identified by the request Uniform Resource Identifier (URI). The PROPFIND Method can be used on collection and property resources.
When a large "If" header is given with WebDAV PROPFIND, ScStoragePathFromUrl function is unable to parse it leading to a buffer overflow.

The exploit code in the PoC has shellcode which is sprayed in memory.This shellcode can be used to execute malicious command on the vulnerable system.

SonicWALL Threat Research Team has researched this vulnerability and released following signature to protect their customers.

  • IPS 12697 : Microsoft IIS Buffer Overflow (CVE-2017-7269)
  • WAF 1664: Internet Information Services (IIS) WebDAV Buffer Overflow