CVE-2015-1701
Microsoft Win32k Privilege Escalation Vulnerability
Description
CVE-2015-1701 is a HIGH vulnerability in Microsoft Win32k, carrying a CVSS 3.1 score of 7.8. An unspecified vulnerability exists in the Win32k.sys kernel-mode driver in Microsoft Windows Server that allows a local attacker to execute arbitrary code with elevated privileges. Exploitation typically occurs through a local attacker or malware running on the system that leverages this kernel-level vulnerability to escalate from user-level to SYSTEM privileges, enabling full control over the compromised host. This CVE is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog with a remediation deadline of 2022-03-24. CISA has confirmed ransomware associations, significantly elevating the threat profile. With an EPSS score of 0.89657 (99.56th percentile), this vulnerability exhibits substantial real-world exploitation activity.
KEV Information
CVSS Score
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HOpen in CalculatorAffected Products
| Vendor | Product | Version |
|---|---|---|
| microsoft | windows 2003 server | -; r2 |
| microsoft | windows 7 | - |
| microsoft | windows server 2008 | - |
| microsoft | windows vista | - |
Multiple CVSS Assessments
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
References
- http://seclists.org/fulldisclosure/2020/May/34(Broken Link, Mailing List, Third Party Advisory)
- http://twitter.com/symantec/statuses/590208710527549440(Press/Media Coverage)
- http://www.securityfocus.com/bid/74245(Broken Link, Third Party Advisory, VDB Entry)
- http://www.securitytracker.com/id/1032155(Broken Link, Third Party Advisory, VDB Entry)
- https://docs.microsoft.com/en-us/security-updates/securitybulletins/2015/ms15-051(Patch, Vendor Advisory)
- https://www.exploit-db.com/exploits/37049/(Exploit, Third Party Advisory, VDB Entry)
- https://www.exploit-db.com/exploits/37367/(Exploit, Third Party Advisory, VDB Entry)
- https://www.fireeye.com/blog/threat-research/2015/04/probable_apt28_useo.html(Third Party Advisory)
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2015-1701(US Government Resource)
Weakness Type
Vulnerability Classification
At the time of analysis, no specific CWE classification has been formally assigned to CVE-2015-1701. The vulnerability in Microsoft Win32k involves a flaw that allows attackers to compromise affected systems. The vulnerability resides in the Win32k.sys kernel-mode driver, which handles window management and graphics rendering in Microsoft Windows. The kernel-mode driver processes requests from user-space applications and translates them into kernel operations. A flaw in how the driver processes certain operations allows a local attacker to corrupt kernel memory structures, ultimately achieving arbitrary code execution with SYSTEM-level privileges. Kernel-mode vulnerabilities are particularly severe because they operate at the highest privilege level in the Windows security model, bypassing all user-space security controls. Despite the absence of a formal CWE designation, the vulnerability's inclusion in the CISA KEV catalog and its CVSS score of 7.8 confirm that it poses a serious, actively exploited threat.
The HIGH severity rating indicates that successful exploitation has substantial consequences for affected organizations. Given the widespread deployment of Microsoft Win32k, this vulnerability represents a significant attack surface that demands immediate attention regardless of formal weakness classification.
Impact Analysis
CVE-2015-1701 carries a CVSS 3.1 score of 7.8 (HIGH) with the following impact characteristics.
Confidentiality (HIGH): An attacker who successfully exploits this vulnerability gains access to all data accessible by the affected component. In the context of Microsoft Win32k, this can include sensitive configuration data, user credentials, proprietary business information, and any data the application processes or stores.
Integrity (HIGH): Successful exploitation enables an attacker to modify, corrupt, or destroy data within the affected system. This includes the potential to tamper with system files, install backdoors or persistent malware, alter critical configurations, and manipulate application logic to serve malicious purposes.
Availability (HIGH): The vulnerability can be exploited to cause complete denial of service, rendering the affected system or application unavailable to legitimate users. System crashes, infinite loops, or resource exhaustion may persist until manual administrative intervention restores normal operation.
Scope (Unchanged): The exploitation impact is contained within the security scope of the vulnerable component itself. While the damage within that scope can be severe with full compromise of the affected application, lateral impact on other systems requires additional exploitation steps.
With an EPSS score of 0.89657 (99.56th percentile), this vulnerability ranks among the most likely to be exploited in the wild, placing it well above the vast majority of all cataloged vulnerabilities in terms of real-world exploitation activity.
Exploit Maturity
CVE-2015-1701 demonstrates significant exploit maturity with confirmed active exploitation in the wild.
Active exploitation: This vulnerability is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, confirming that it has been observed being actively exploited by threat actors. The KEV designation mandates federal agencies to apply remediation within a defined timeframe and serves as a strong signal of real-world risk.
Ransomware association: CISA's KEV catalog confirms a known association between CVE-2015-1701 and ransomware campaigns. Ransomware operators have incorporated exploits targeting this vulnerability into their attack chains, using it for initial access or privilege escalation to deploy ransomware payloads across enterprise environments.
Public exploits: Public exploit code is available, significantly lowering the barrier for exploitation. Known exploit references include entries on Exploit-DB and additional vulnerability databases. The availability of weaponized code means that both sophisticated threat actors and less-skilled attackers can target this vulnerability with minimal development effort.
KEV remediation deadline: CISA set a remediation deadline of 2022-03-24 for federal agencies, underscoring the urgency of patching. Organizations beyond the federal sector should treat this deadline as a strong indicator of the risk level and prioritize remediation accordingly.
Remediation
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Apply vendor-provided security patches immediately. Apply updates per vendor instructions. Consult the official security advisory for specific patch versions and deployment guidance.
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Verify affected product versions in your environment. Affected products include: Windows 2003 Server (-; r2), Windows 7, Windows Server 2008, Windows Vista. Conduct an inventory of all instances across your organization to ensure comprehensive patch coverage and prevent any unpatched systems from remaining exposed.
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Implement interim mitigations if immediate patching is not feasible. Apply the principle of least privilege to reduce the potential impact. Restrict local access to systems running affected software, implement application control measures, and consider network segmentation to limit lateral movement potential.
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Enable enhanced monitoring and detection. Configure intrusion detection systems and endpoint detection and response (EDR) tools to detect exploitation attempts targeting CVE-2015-1701. Review security logs for indicators of compromise and establish alerting for anomalous behavior on systems running affected software.
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Conduct a post-patch vulnerability assessment. After applying patches, verify that the remediation was effective by running vulnerability scans against all previously affected systems. Confirm the vulnerability is no longer present and ensure no instances were missed during deployment.
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Assess for signs of prior compromise. Given the confirmed ransomware association, investigate whether this vulnerability may have already been exploited in your environment. Check for unusual process activity, unauthorized file modifications, anomalous network traffic patterns, and unexpected lateral movement between systems.
Technical Details
CVE-2015-1701 is a high-severity vulnerability affecting Microsoft Win32k. An unspecified vulnerability exists in the Win32k.sys kernel-mode driver in Microsoft Windows Server that allows a local attacker to execute arbitrary code with elevated privileges.
Attack Vector: The attack vector is LOCAL, meaning exploitation requires the attacker to have local access to the target system or to trick a user into performing a local action such as opening a malicious file. While this limits remote exploitation, it remains highly exploitable through social engineering and phishing campaigns.
Attack Complexity: The attack complexity is LOW. Exploitation does not require specialized conditions, race conditions, or extensive preparation — making it accessible to a broad range of attackers including those with limited technical sophistication.
Prerequisites: The attacker requires low-level privileges on the target system. No user interaction is required for exploitation.
Underlying mechanism: The vulnerability resides in the Win32k.sys kernel-mode driver, which handles window management and graphics rendering in Microsoft Windows. The kernel-mode driver processes requests from user-space applications and translates them into kernel operations. A flaw in how the driver processes certain operations allows a local attacker to corrupt kernel memory structures, ultimately achieving arbitrary code execution with SYSTEM-level privileges. Kernel-mode vulnerabilities are particularly severe because they operate at the highest privilege level in the Windows security model, bypassing all user-space security controls.
Affected products: Windows 2003 Server (-; r2), Windows 7, Windows Server 2008, Windows Vista. Organizations should cross-reference their deployed versions against this list to assess their exposure to this vulnerability.
Frequently Asked Questions
What is CVE-2015-1701?
CVE-2015-1701 is a high-severity vulnerability (CVSS 7.8) affecting Microsoft Win32k. An unspecified vulnerability exists in the Win32k.sys kernel-mode driver in Microsoft Windows Server that allows a local attacker to execute arbitrary code with elevated privileges. It is listed in CISA's Known Exploited Vulnerabilities catalog, confirming active exploitation in the wild. The vulnerability has confirmed associations with ransomware campaigns.
Which products are affected by CVE-2015-1701?
The vulnerability affects Microsoft products including Windows 2003 Server, Windows 7, Windows Server 2008, Windows Vista. Affected versions include -; r2. Organizations should consult the vendor's security advisory for the complete list of affected versions and available patches.
How do I fix CVE-2015-1701?
Apply updates per vendor instructions. Refer to the official vendor security advisory for specific patch downloads and deployment instructions. If immediate patching is not possible, implement interim mitigations such as restricting access to the vulnerable component, enabling enhanced monitoring, and educating users about potential attack vectors. Verify remediation effectiveness with post-patch vulnerability scanning.
How severe is CVE-2015-1701?
CVE-2015-1701 is rated HIGH with a CVSS 3.1 score of 7.8. Its EPSS score of 0.89657 places it in the 99.56th percentile for exploitation likelihood, meaning it is more likely to be exploited than 99.6% of all known vulnerabilities. CISA has confirmed ransomware association, and the KEV remediation deadline was 2022-03-24. The combination of active exploitation, ransomware use, and high EPSS makes this vulnerability a top-priority remediation target for all affected organizations.
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