CVE-2015-2546
Microsoft Win32k Memory Corruption Vulnerability
Description
CVE-2015-2546 is a high-severity memory corruption vulnerability affecting Microsoft Win32k. The kernel-mode driver in Microsoft Windows OS and Server allows local users to gain privileges via a crafted application. This vulnerability has been associated with ransomware campaigns, heightening its risk profile. CISA has added CVE-2015-2546 to the Known Exploited Vulnerabilities catalog, confirming active exploitation in the wild. With an EPSS score of 39.93% (97.3rd percentile), this vulnerability has a significant probability of being exploited.
KEV Information
CVSS Score
CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:HOpen in CalculatorAffected Products
| Vendor | Product | Version |
|---|---|---|
| microsoft | windows 10 1507 | - |
| microsoft | windows 7 | - |
| microsoft | windows 8 | - |
| microsoft | windows 8.1 | - |
| microsoft | windows rt | - |
| microsoft | windows rt 8.1 | - |
| microsoft | windows server 2008 | -; r2 |
| microsoft | windows server 2012 | -; r2 |
| microsoft | windows vista | - |
References
- http://www.securityfocus.com/bid/76608(Broken Link, Third Party Advisory, VDB Entry)
- http://www.securitytracker.com/id/1033485(Broken Link, Third Party Advisory, VDB Entry)
- https://docs.microsoft.com/en-us/security-updates/securitybulletins/2015/ms15-097(Patch, Vendor Advisory)
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2015-2546(US Government Resource)
Weakness Type
CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer
Improper Restriction of Operations within the Bounds of a Memory Buffer occurs when software performs operations on a memory buffer but can read from or write to a memory location that is outside the intended boundary of the buffer. This is the parent category for many specific buffer error types including buffer overflows (CWE-120), buffer underflows, out-of-bounds reads (CWE-125), and out-of-bounds writes (CWE-787). In the case of CVE-2015-2546, this weakness manifests in Microsoft Win32k where the kernel-mode driver in Microsoft Windows OS and Server allows local users to gain privileges via a crafted application.
Learn more: CWE-119 — Improper Restriction of Operations within the Bounds of a Memory Buffer
Impact Analysis
CVE-2015-2546 represents a significant threat to organizations using Microsoft Win32k, carrying a CVSS score of 8.2. Successful exploitation can fully compromise the confidentiality, integrity, and availability of affected systems. Attackers can access sensitive data, modify system configurations or data, and disrupt service availability. The changed scope indicates that exploitation can impact resources beyond the vulnerable component itself, potentially affecting other systems or security domains. The documented association with ransomware campaigns makes this vulnerability particularly dangerous, as threat actors actively leverage it for initial access or privilege escalation in ransomware operations.
Exploit Maturity
CVE-2015-2546 is listed in the CISA Known Exploited Vulnerabilities catalog, confirming real-world exploitation. The EPSS score of 39.93% (97.3rd percentile) indicates a significant probability of exploitation in the wild. This vulnerability has been linked to ransomware campaigns, indicating that well-resourced threat actors are actively incorporating it into their attack chains.
Remediation
- Apply vendor patches immediately as required by CISA KEV: Apply updates per vendor instructions. Update Microsoft Win32k to the latest available version that addresses this vulnerability.
- Until the patch is applied, enforce the principle of least privilege by limiting local user access to only those who require it, and restrict the ability to execute untrusted applications on affected systems.
- Given the ransomware association, ensure endpoint detection and response (EDR) solutions are active on all affected systems and monitor for indicators of compromise including unusual process execution, file encryption activity, and lateral movement.
- Verify the patch deployment across all instances of Microsoft Win32k in your environment using vulnerability scanning to confirm no systems remain exposed.
- Review and update your organization's vulnerability management process to ensure CISA KEV entries with a remediation deadline of 2022-04-05 are addressed within the required timeframe.
Technical Details
CVE-2015-2546 is classified under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer) affecting Microsoft Win32k. The kernel-mode driver in Microsoft Windows OS and Server allows local users to gain privileges via a crafted application. The vulnerability is exploitable with local access to the target system, with low attack complexity, requiring low-level privileges, and requiring user interaction such as opening a malicious file or visiting a crafted webpage. The CVSS 3.1 base score of 8.2 (HIGH) reflects high confidentiality impact, high integrity impact, and high availability impact, with the potential to affect resources beyond the vulnerable component.
Frequently Asked Questions
Is CVE-2015-2546 being actively exploited?
Yes. CVE-2015-2546 is listed in the CISA Known Exploited Vulnerabilities catalog, confirming active exploitation in the wild. The EPSS score of 39.93% (97.3rd percentile) indicates a significant probability of exploitation. This vulnerability has also been associated with ransomware campaigns.
What products are affected by CVE-2015-2546?
CVE-2015-2546 primarily affects Microsoft Win32k, as well as Microsoft Windows 10 1507, Microsoft Windows 7, Microsoft Windows 8. Organizations should check whether any instances of the affected software are running in their environment.
How do I fix CVE-2015-2546?
Apply updates per vendor instructions. Until the update is applied, limit local access privileges and monitor for suspicious activity on affected systems.
How severe is CVE-2015-2546?
CVE-2015-2546 has a CVSS 3.1 score of 8.2, rated HIGH. This high severity rating indicates significant potential impact on affected systems. The association with ransomware campaigns further elevates the operational risk posed by this vulnerability.
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