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Vulnerability Notice: CVE-2015-2360

Vendor:
Microsoft

Affected Product:
Windows_8.1, Windows_7

CVSS SCORE:
8.8 of 10 (High)

Risk Index:
9.3 of 10 (Critical)

Description

A critical vulnerability has been identified in the kernel-mode drivers (win32k.sys) of multiple Microsoft Windows products. This vulnerability, known as “Win32k Elevation of Privilege Vulnerability,” allows local users to gain elevated privileges or cause a denial of service (DoS) through memory corruption by running a specially crafted application.

 

Affected Product(s)

  • Microsoft Windows Server 2003 SP2,
  • Windows Server 2003 R2 SP2,
  • Windows Vista SP2,
  • Windows Server 2008 SP2,
  • Windows Server 2008 R2 SP1,
  • Windows 7 SP1,
  • Windows 8,
  • Windows 8.1,
  • Windows Server 2012 Gold,
  • Windows Server 2012 R2,
  • Windows RT Gold, and
  • Windows RT 8.1

 

Technical Details

The vulnerability in question (CVE-2015-2360) allows local users to escalate privileges and potentially execute arbitrary code within the affected system’s kernel. This vulnerability stems from a memory corruption issue within the win32k.sys component of the Windows kernel-mode drivers. Memory corruption, in this context, means that an incorrectly handled memory operation can be exploited to overwrite critical memory regions, leading to arbitrary code execution or system instability.

The issue resides in the way win32k.sys handles memory elements and users inputs, including arbitrary memory dereferences and user mode inputs. Exploitability is high as it lies deep within the core system drivers that have elevated privileges. This environment facilitates threat actors to gain critical system control if capable of injecting and running exploit code.

Several technical reports pointed out that the Duqu 2.0 malware extensively utilized this vulnerability for its sophisticated espionage campaigns, as detailed in numerous advanced persistent threat (APT) attacks.

The malware leveraged CVE-2015-2360 to gain privileged kernel access, allowing it to activate and operate without detection for extended periods. The attacker used a combination of zero-day exploits and sophisticated malware to compromise high-profile targets such as Kaspersky Labs.

The exploit process can be broken down into the following stages:

  • Host Preparation: The attacker tricks a user into executing malicious user-mode code, often delivered via phishing attacks.
  • Exploit Code Setup: The malicious code collects necessary information about the target system to adapt the exploit accordingly.
  • Vulnerability Exploitation: The exploit code then uses the collected information to abuse the vulnerability, overwriting or injecting malicious code into the kernel space.
  • Payload Execution: Finally, upon successful exploitation, the payload executes, granting the attacker elevated privileges and executing arbitrary code within the kernel.

This vulnerability underscores the risk posed by kernel-level exploits and the efforts needed to safeguard systems. Threat actors’ exploitation techniques continually evolve, indicating the necessity for robust security practices and timely application of patches.

 

Weakness

The primary weakness associated with this vulnerability is classified under two types:

  • Improper Restriction of Operations within the Bounds of a Memory Buffer (CWE-119): This weakness refers to the insufficient checks on memory boundaries when copying data, leading to potential buffer overflows.
  • Use After Free (CWE-416): This occurs when previously freed memory is still referenced, potentially allowing attackers to execute arbitrary code via dangling pointers. Both weaknesses highlight critical issues in memory management within the win32k.sys component, posing significant risk for privilege escalation and remote code execution.

 

Impact Assessment

If exploited, this vulnerability could allow an attacker to gain unauthorized access to sensitive data or execute arbitrary code on the affected system. This access could lead to full administrative control, with the ability to compromise system integrity, confidentiality, and availability. Attackers may also install further malware, exfiltrate data, or leverage the compromised system to initiate wider network attacks, emphasizing the high risk and impact associated with this vulnerability.

 

Active Exploitation

We have observed activity from advanced adversary groups exploiting this vulnerability, notably the Duqu 2.0 malware utilized by nation-state actors in sophisticated espionage campaigns. Duqu 2.0 is known to leverage CVE-2015-2360 among other exploits to infiltrate and remain undetected in targeted systems over extended periods.

 

Ransomware Association

Though primarily linked with espionage, there are intersections where the exploited vulnerabilities, including CVE-2015-2360, can aid in ransomware deployments. The access achieved through this vulnerability can facilitate ransomware to gain necessary privileges, encrypt critical data, and demand ransom, demonstrating the evolving landscape of threats deploying these exploits.

 

Mitigation and Resolution

We have released a patch that addresses this vulnerability. Please update to the latest versions as detailed in Microsoft Bulletin MS15-061 to mitigate the exploitation risk associated with CVE-2015-2360. Applying the patch promptly is essential to safeguard systems against potential attacks leveraging this vulnerability.

 

Recommendations

  • We strongly recommend that all customers apply the latest patch as soon as possible.
  • Detailed steps to implement the patch are available in the official Microsoft Bulletin MS15-061.
  • Regularly review and update security configurations to mitigate potential exploitation.
  • Conduct periodic security audits and vulnerability assessments to identify and address security gaps.
  • Educate users on recognizing phishing attempts and employing safe practices online.
  • Utilize advanced threat detection and response solutions to monitor for indicators of compromise (IoCs) related to kernel-mode exploits.

 

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