Zero-day vulnerability in Windows

Path traversal
CVE-2015-0016

The vulnerability was being used in CNACOM campaign targeting government organization in Taiwan.

Known malware:

Exploit.Win32.CVE-2015-0016.

Vulnerability details

Advisory: SB2015011301 - Privilege escalation in Microsoft Windows

Vulnerable component: Windows

CVE-ID: CVE-2015-0016

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

CWE-ID: CWE-22 - Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

Description:

The vulnerability allows a remote attacker to gain elevated privileges on the target system.

The weakness exists due to insufficient validation of user-supplied input within TS WebProxy Windows component. A remote attacker can trick the victim into downloading a specially crafted file and execute it with privileges of the current user.  

Successful exploitation of the vulnerability may result in full control of the vulnerable system.

Note: the vulnerability was being actively exploited.

Known APT campaigns:

CNACOM campaign

The campaign mainly targeted Taiwanese organizations and supposedly has Chinese origin.

Public Exploits:

- Microsoft Remote Desktop Services - Web Proxy IE Sandbox Escape (MS15-004) (Metasploit) [Exploit-DB]

External links:

https://technet.microsoft.com/library/security/ms15-004
http://blog.trendmicro.com/trendlabs-security-intelligence/cve-2015-0016-escaping-the-internet-explo...
https://www.symantec.com/security_response/vulnerability.jsp?bid=71965
http://www.securityweek.com/china-linked-spies-target-taiwan-ie-exploit
http://securityaffairs.co/wordpress/33153/cyber-crime/fessleak-malvertising-campaign.html
http://securityaffairs.co/wordpress/54093/intelligence/cnacom-campaign.html

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.