CVE-2021-21017 is a high-severity vulnerability affecting Adobe Acrobat and Reader, specifically in versions 2020.013.20074 and earlier, 2020.001.30018 and earlier, and 2017.011.30188 and earlier. This vulnerability allows for a heap-based buffer overflow, enabling an unauthenticated attacker to achieve arbitrary code execution in the context of the current user. Crucially, exploitation requires user interaction, as a victim must open a malicious file to trigger the vulnerability.
With a CVSS score of 8.8, this vulnerability poses a significant risk to organizations using affected versions of Adobe software. The attack vector is network-based, requiring low complexity and no privileges, but necessitating user interaction. This combination increases the likelihood of successful exploitation, making immediate remediation critical.
Organizations should prioritize patching these vulnerabilities to mitigate potential risks. Given its classification as actively exploited in the wild, it is imperative that defenders take swift action to protect their environments from potential attacks.
As malicious actors increasingly target known vulnerabilities, timely updates and user education about the risks of opening untrusted files are essential strategies for reducing exposure.
Vulnerability Details
The vulnerability in question is classified as a heap-based buffer overflow, with the official description noting that affected versions of Adobe Acrobat Reader DC are vulnerable due to improper handling of input. The CVSS 3.1 score of 8.8 indicates a high level of severity, reflecting the potential for significant impacts on confidentiality, integrity, and availability.
The affected products include Acrobat, Acrobat DC, Acrobat Reader, and Acrobat Reader DC. Adobe published the vulnerability on February 11, 2021. For this vulnerability, the CWE classifications include CWE-122 and CWE-787, which relate to improper restriction of operations within the bounds of a memory buffer.
Technical Analysis
The root cause of CVE-2021-21017 stems from improper input validation that leads to a heap-based buffer overflow. Attackers may exploit this vulnerability through a network-based attack vector, requiring user interaction to open a crafted file.
The attack complexity is classified as low, and no privileges are required for exploitation. However, user interaction is necessary, which could limit the attack surface to some extent. The potential impacts include high confidentiality, integrity, and availability risks, due to the ability to execute arbitrary code.
Risk & Impact Analysis
Risk to organizations includes unauthorized access and control over affected systems, leading to potential data breaches or loss of sensitive information. The blast radius for this vulnerability encompasses all users of affected Adobe products, particularly in environments where users may inadvertently open malicious files.
Given the high CVSS score and its presence in the Known Exploited Vulnerabilities (KEV) catalog, organizations should treat this vulnerability with utmost urgency. Immediate patching is critically important to reduce the risk of exploitation.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | Yes |
Public PoC | Yes |
Actively Exploited | Yes |
Ransomware Use | No |
Affected Versions
The affected versions of Adobe products include Acrobat Reader DC versions 2020.013.20074 and earlier, 2020.001.30018 and earlier, and 2017.011.30188 and earlier. Organizations should ensure that they are running patched versions to mitigate this vulnerability.
Mitigation & Remediation
Organizations must apply the patches provided by Adobe to remediate this vulnerability. Regular updates to software, including Adobe Acrobat and Reader, should be part of a comprehensive security strategy. For those unable to immediately apply patches, implementing strict network controls and user education on the risks of opening untrusted files are essential.
For additional guidance on effective security practices, organizations can refer to penetration testing services that help identify potential vulnerabilities.
Detection Guidance
Organizations should monitor logs for indicators of exploitation attempts, including unexpected application crashes or anomalous file access patterns. Additionally, behavioral anomalies in user actions, especially those related to file openings, should be flagged for review.
AppSecure Threat Intelligence Insight
CVE-2021-21017 serves as a reminder of the importance of user interaction in vulnerability exploitation. As attackers continue to leverage known vulnerabilities, organizations must remain vigilant in their security practices. Ensuring timely updates, user education, and proactive security measures can significantly reduce the risk of exploitation.
For comprehensive security assessments, organizations may find value in engaging with professional services. For further reading on vulnerability management, consider reviewing the vulnerability management program to enhance their defensive posture.
In addition, understanding patterns in exploitation can be beneficial. The analysis of trends in vulnerabilities, such as in the case of CVE-2021-21017, highlights the need for ongoing vigilance and adaptation in security strategies. For further insights, organizations can explore the penetration testing methodology as a means to proactively identify and mitigate risks.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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