Zero-day vulnerability in Windows

Privilege escalation
CVE-2016-7255

The zero-day was being actively exploited by Russian hackers (APT28, Fancy Bear, Pawn Storm, Sednit, Tsar Team, and Sofacy).

Vulnerability details

Advisory: SB2016110101 - Privilege escalation in Windows 10

Vulnerable component: Windows

CVE-ID: CVE-2016-7255

CVSSv3 score: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H/E:H/RL:U/RC:C

CWE-ID: CWE-119 - Memory corruption

Description:

The vulnerability allows a local user to gain elevated privileges on the target system.

The weakness is due to improper handling of objects in memory by win32k.sys. By sending a specially crafted system call NtSetWindowLongPtr(), a local attacker can set index GWLP_ID to WS_CHILD value on a window handle with GWL_STYLE and execute arbitrary code with system privileges.

Successful explotation of the vulnerability results in privilege escalation.

Note: this vulnerability is being actively exploited in the wild.

Public Exploits:

- Microsoft Windows Kernel - 'win32k.sys' 'NtSetWindowLongPtr' Privilege Escalation (MS16-135) (2) [Exploit-DB]

- Microsoft Windows Kernel - 'win32k.sys' 'NtSetWindowLongPtr' Privilege Escalation (MS16-135) (1) [Exploit-DB]

- Microsoft Windows Kernel - win32k Denial of Service (MS16-135) [Exploit-DB]

- Microsoft Windows - 'Win32k' Local Privilege Escalation [Exploit-DB]

External links:

https://www.symantec.com/security_response/writeup.jsp?docid=2016-110821-3527-99
https://technet.microsoft.com/library/security/ms16-135
https://security.googleblog.com/2016/10/disclosing-vulnerabilities-to-protect.html
http://www.netsec.news/patch-tuesday-sees-68-microsoft-vulnerabilities-fixed/
https://securingtomorrow.mcafee.com/mcafee-labs/digging-windows-kernel-privilege-escalation-vulnerab...
http://securityaffairs.co/wordpress/53242/hacking/cve-2016-7255-zero-day.html
http://blog.trendmicro.com/trendlabs-security-intelligence/one-bit-rule-system-analyzing-cve-2016-72...
https://cyware.com/news/one-bit-to-rule-a-system-analyzing-cve-2016-7255-exploit-in-the-wild-84cb5e1...
http://www.darkreading.com/endpoint/microsoft-november-security-updates-include-fix-for-zero-day-fla...
https://www.grahamcluley.com/pawn-storm-microsoft-zero-day/
https://nakedsecurity.sophos.com/2016/11/09/november-patch-tuesday-fixes-controversial-windows-0-day...
http://sensorstechforum.com/cve-2016-7255-67-vulnerabilities-addressed-microsoft/

About zero-day vulnerabilities

Zero-day vulnerability is an undisclosed vulnerability in software that hackers can exploit to compromise computer programs, gain unauthorized access to sensitive data, penetrate networks, etc. We consider vulnerability a zero-day when there is no solution provided from software vendor and the vulnerability is being actively exploited by malicious actors.

Zero-day candidate is a potential zero-day vulnerability in software which might have been used in targeted attacks, however there is no evidence to support this suggestion.