CVE-2021-36934 is a high-severity elevation of privilege vulnerability affecting Microsoft Windows products. This vulnerability allows attackers to exploit overly permissive Access Control Lists (ACLs) on critical system files, including the Security Accounts Manager (SAM) database. With successful exploitation, an attacker can run arbitrary code with SYSTEM privileges, potentially leading to unauthorized access, installation of malicious software, or modification of sensitive data. The CVSS score for this vulnerability is 7.8, indicating a high level of risk to organizations.
Organizations should prioritize patching immediately to mitigate the risks associated with this vulnerability. An attacker must have the ability to execute code on a victim system to exploit this vulnerability. Notably, simply installing the security update is insufficient; organizations must also manually delete all shadow copies of system files, including the SAM database, to fully mitigate this vulnerability.
Given the potential for significant damage that an attacker could inflict by gaining SYSTEM privileges, it is critical for organizations to act swiftly. This vulnerability has been confirmed to be actively exploited, which heightens the urgency for organizations to assess their systems and apply necessary patches.
The vulnerability was published on July 22, 2021, and has been analyzed thoroughly. Its exploitation is classified as critical, and it is listed in the Known Exploited Vulnerabilities (KEV) catalog, further emphasizing the need for immediate remediation.
Vulnerability Details
The CVE-2021-36934 vulnerability arises from overly permissive ACLs on system files, which can be manipulated by an attacker. The vulnerability is characterized as an elevation of privilege issue. The CVSS score of 7.8 indicates a high severity level, underscoring the critical nature of the vulnerability. The affected products include several versions of Windows 10, specifically 1809, 1909, 2004, 20H2, and 21H1.
Published on July 22, 2021, the vulnerability has been classified under the CWE as a primary weakness. Organizations are encouraged to stay informed of any updates or patches released by Microsoft for this vulnerability.
Technical Analysis
The root cause of CVE-2021-36934 is the improper implementation of Access Control Lists (ACLs) on sensitive system files. This misconfiguration allows unauthorized users to gain access to the SAM database, effectively granting them SYSTEM-level privileges. The attack vector is local, requiring an attacker to have code execution capabilities on the target machine. The attack complexity is low, with no user interaction required, making this vulnerability particularly dangerous.
Exploitation of this vulnerability leads to a high impact on confidentiality, integrity, and availability, as it allows attackers to manipulate critical system resources and sensitive information. Organizations must understand the potential blast radius of this vulnerability and implement appropriate defenses.
Risk & Impact Analysis
The real-world risk associated with CVE-2021-36934 is significant. Successful exploitation could lead to a complete compromise of affected systems, allowing attackers to install malicious software, exfiltrate sensitive data, or disrupt operations. The potential for damage extends to all organizations using the impacted versions of Windows 10.
Given the high CVSS score and its inclusion in the KEV catalog, organizations must assess their exposure to this vulnerability and prioritize remediation efforts. The urgency is critical, and organizations should address this vulnerability immediately to prevent potential exploitation.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | Yes |
Public PoC | Yes |
Actively Exploited | Yes |
Ransomware Use | No |
Affected Versions
The affected versions of Microsoft Windows include:
• Windows 10 version 1809 (up to 10.0.17763.2114) • Windows 10 version 1909 (up to 10.0.18363.1734) • Windows 10 version 2004 (up to 10.0.19041.1165) • Windows 10 version 20H2 (up to 10.0.19042.1165) • Windows 10 version 21H1 (up to 10.0.19043.1165)
Mitigation & Remediation
To mitigate CVE-2021-36934, organizations must apply the latest security updates from Microsoft. It is essential to follow up by manually deleting all shadow copies of system files, including the SAM database, to ensure complete remediation. This step is crucial as merely installing the update will not suffice.
For more information on effective remediation strategies, organizations can refer to the following resources: penetration testing services that can assist in validating updates and assessing security posture.
Detection Guidance
Organizations should monitor for the following indicators to detect potential exploitation of CVE-2021-36934:
• Log indicators of unauthorized access attempts to system files. • Behavioral anomalies indicating privilege escalation. • Unusual access patterns to the SAM database or related registry hives.
AppSecure Threat Intelligence Insight
CVE-2021-36934 highlights a critical issue in security configuration management. The discovery of this elevation of privilege vulnerability demonstrates the importance of proper ACL implementation on sensitive system files. Security teams must remain vigilant and continuously assess their configurations to mitigate similar risks.
To gain further insights into vulnerability management, organizations can explore our vulnerability management program design which can help in establishing a more robust security posture.
Additionally, organizations should consider engaging in penetration testing to proactively identify and remediate vulnerabilities before they can be exploited.
Finally, understanding the patterns of exploitation can inform better security practices. Organizations can refer to our red teaming guide for insights into how attackers operate and how to defend against such vulnerabilities.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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