CVE-2021-35939 is a medium-severity vulnerability found in the Red Hat RPM package manager. The vulnerability arises from an incomplete fix for previously reported vulnerabilities, specifically CVE-2017-7500 and CVE-2017-7501. This flaw can be exploited by local unprivileged users who own an ancestor directory, potentially allowing them to gain root privileges.
The CVSS score of this vulnerability is 6.7, indicating a medium severity. The attack vector is local, and the attack complexity is low, meaning that successful exploitation does not require significant technical skills. Organizations should be aware that the vulnerability poses a risk to data confidentiality, integrity, and system availability.
As this vulnerability has not been confirmed to have a public exploit, and it does not appear in the Known Exploited Vulnerabilities (KEV) catalog, it is essential for organizations to assess their exposure and prioritize remediation efforts.
Given the potential for root privilege escalation, organizations should address this vulnerability in their priority patch cycle and ensure that updates are applied promptly.
Vulnerability Details
The vulnerability was published on August 26, 2022, and affects the RPM package manager and Red Hat Enterprise Linux 8.0. The specific weakness is classified as CWE-59, which relates to improper link resolution before dereference. This vulnerability is particularly concerning due to the high impact on confidentiality, integrity, and availability.
Technical Analysis
The root cause of CVE-2021-35939 lies in the incomplete implementation of checks for unsafe symlinks, which only applies to the parent directory of the file being created. This flaw allows a local unprivileged user to exploit it if they control another ancestor directory.
The attack vector is local, meaning that an attacker must have access to the targeted system. The complexity of the attack is low, requiring minimal skill to exploit. The privileges required for exploitation are high, as the attacker must have ownership of an ancestor directory. No user interaction is required for the exploit to succeed.
This vulnerability can lead to a complete compromise of confidentiality, integrity, and availability of the affected system, making it critical for organizations to take swift action.
Risk & Impact Analysis
Risk to organizations includes potential unauthorized access to sensitive data and system controls. Given that attackers may leverage this vulnerability to escalate privileges, the blast radius could be significant, impacting multiple systems if not contained effectively.
With an EPS score of approximately 0.002, this vulnerability falls into the lower percentile of risk. However, organizations should not underestimate the potential impact, especially in environments where the RPM package manager is widely used.
Organizations should prioritize patching immediately to mitigate the risk posed by this vulnerability. It is essential to stay vigilant and monitor for any signs of exploitation.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The affected versions of the RPM package manager include all versions prior to 4.18. Additionally, Red Hat Enterprise Linux 8.0 is also impacted by this vulnerability. Organizations should verify their installations to ensure they are updated.
Mitigation & Remediation
To remediate this vulnerability, organizations should apply the latest security patches provided by Red Hat. Specifically, upgrading to RPM 4.18 or later will mitigate the risk associated with CVE-2021-35939. If a patch is not immediately available, organizations should implement configuration hardening by restricting user access to sensitive directories.
Monitoring systems for any unauthorized access attempts and ensuring that security practices are followed during patch management will also help minimize potential risks. For further guidance, organizations can consider engaging in penetration testing to validate their security posture.
Detection Guidance
Organizations should monitor logs for unusual file creation attempts or directory access patterns that deviate from normal behavior. Behavioral anomalies, such as unauthorized changes to directory permissions or unexpected user privilege escalations, should also trigger alerts.
Additionally, network signatures that detect unusual traffic patterns related to local privilege escalation attempts should be established to enhance detection capabilities.
AppSecure Threat Intelligence Insight
CVE-2021-35939 highlights the importance of thorough patching and security practices in maintaining system integrity. It demonstrates a common trend where vulnerabilities arise from incomplete fixes of previous issues.
Security teams should adopt a proactive approach to vulnerability management by implementing a robust vulnerability management program that includes regular assessments and timely patching cycles.
Understanding how vulnerabilities are exploited can help organizations bolster their defenses. Engaging in penetration testing methodology provides insights into potential attack vectors and assists in identifying weaknesses before they can be exploited.
Ultimately, organizations should remain vigilant and informed about emerging threats to ensure a resilient security posture.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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