Mitigating Remote Code Execution in "HTTP.sys" (CVE-2015-1635)

A critical Windows vulnerability in its HTTP stack ("HTTP.sys"), which was resolved in a recent Microsoft's Patch Tuesday release, could allow remote attackers to execute code on an IIS server with the privileges of the System account. A Proof-of-Concept code to check the existence of this vulnerability was soon to follow. Remote attackers could exploit the way "HTTP.sys" parses requests with a Range header including a very large byte range to crash the server or potentially run their shellcode.

http://www.exploit-db.com/exploits/36773/

 

                        

                                                                                POC Information

 

                        

                                                                    Bug details according to the POC

 

More details on the available patch could be found in Microsoft’s security builletin MS15-034:

https://technet.microsoft.com/library/security/MS15-034

 

Following user-defined signature will detect and mitigate attempts to exploit this vulnerability while using ASM.

ASM versions including and above 11.2.x:

headercontent: "range"; nocase; re2:"/bytes\s*=.*?[0-9]{10,}\b/Hi";

 

ASM versions below 11.2.x:

headercontent: "range"; nocase; pcre:"/bytes\s*=.*?[0-9]){10,}\b/Hi";