CVE-2021-39793: High Vulnerability in Google Android

CVE-2021-39793 is a high-severity vulnerability identified in the Android kernel, specifically in the function kbase_jd_user_buf_pin_pages of mali_kbase_mem.c. This vulnerability allows for a possible out-of-bounds write due to a logic error in the code, which could lead to local escalation of privilege. Notably, no additional execution privileges are needed for exploitation, and user interaction is not required. Given its characteristics, organizations utilizing affected versions of Android must prioritize remediation.

With a CVSS score of 7.8, this vulnerability signifies a critical risk to organizations. The potential for attackers to exploit this weakness without user interaction further elevates its severity. Organizations need to be proactive in applying patches to mitigate this risk.

The urgency for defenders is underscored by the vulnerability's presence in the Known Exploited Vulnerabilities (KEV) catalog, indicating that this vulnerability is being actively monitored for exploitation in the wild. Organizations must act swiftly to implement necessary updates.

Risk to organizations includes unauthorized access and potential control over affected systems, emphasizing the importance of immediate action.

Organizations should prioritize patching immediately.

Vulnerability Details

According to the official description, this vulnerability allows for a possible out-of-bounds write in the Android kernel. The specifics of the vulnerability are linked to a logic error in the code, leading to local privilege escalation without requiring additional execution privileges. The vulnerability was published on March 16, 2022, and is classified under CWE-787.

The CVSS score of 7.8 indicates high severity, with a vector string of "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H". This means that the attack vector is local, the complexity is low, and the impact on confidentiality, integrity, and availability is high.

The affected product is the Android kernel, specifically versions managed by Google. Organizations should refer to the vendor's guidance for patching.

Technical Analysis

The root cause of CVE-2021-39793 is a logic error in the code that may lead to an out-of-bounds write. The attack vector is classified as local, meaning that an attacker must have local access to the system to exploit this vulnerability.

The attack complexity is low, which means that attackers do not face significant obstacles in executing their attack. Privileges required for exploitation are low, allowing users with minimal permissions to potentially escalate their privileges. Importantly, no user interaction is required for the exploitation to occur.

The vulnerability has significant impacts on confidentiality, integrity, and availability, as indicated by the CVSS metrics. Attackers may leverage this vulnerability to gain unauthorized access to sensitive data or disrupt service availability.

Risk & Impact Analysis

The real-world deployment risk associated with CVE-2021-39793 is substantial. Organizations utilizing affected versions of the Android kernel face the possibility of local privilege escalation, leading to significant security breaches. The blast radius potential is considerable, as compromised systems could be leveraged for further attacks within the organizational environment.

Organizations should evaluate their exposure based on their use of vulnerable Android versions. The urgency of addressing this vulnerability is high, given its CVSS score and active monitoring in the KEV catalog.

To mitigate risks associated with this vulnerability, organizations must promptly apply security patches as per vendor instructions. Additionally, continuous monitoring for any signs of exploitation is recommended to detect any unauthorized access or changes in system behavior.

Exploitation Status

Affected Versions

The affected version is the Android kernel, specifically identified as vulnerable in the criteria: cpe:2.3:o:google:android:-:*:*:*:*:*:*:*.

Mitigation & Remediation

Organizations should refer to the vendor's advisory to apply the necessary patches. For detailed guidance on implementing security updates, organizations can consult the application security assessment. In cases where immediate patching is not possible, consider implementing workarounds or configuration changes to reduce exposure.

Detection Guidance

Organizations should monitor logs for unusual activities that could indicate exploitation attempts. Behavioral anomalies, such as unexpected privilege escalations or access to sensitive resources, should be flagged for further investigation.

AppSecure Threat Intelligence Insight

The long-term significance of CVE-2021-39793 lies in its representation of common vulnerabilities in device kernel software. This incident sheds light on the importance of regular updates and security assessments to avoid similar exposures in the future.

Security teams can benefit from reviewing existing incident response plans to ensure they are equipped to handle privilege escalation attempts. For further guidance on developing robust security measures, organizations may refer to the penetration testing methodology. Additionally, understanding the patterns of vulnerabilities like this can aid in developing strategic defenses against future threats.

Lastly, investing in continuous security testing can help organizations maintain a proactive stance against emerging vulnerabilities, ensuring their defenses remain resilient.

Known Exploitation Timeline

This vulnerability was added to the KEV catalog on April 11, 2022. Organizations are encouraged to review their systems for this vulnerability actively and apply patches before the due date of May 2, 2022.

EPSS Risk Context

The EPSS score for CVE-2021-39793 is 0.0011, indicating a low probability of exploitation. However, organizations should not overlook this vulnerability due to its potential impact and the active monitoring it receives.