CVE-2021-21219: Medium Vulnerability in Google Chrome

CVE-2021-21219 is a medium-severity vulnerability affecting Google Chrome prior to version 90.0.4430.72. This vulnerability allows uninitialized data in PDFium to be exploited by remote attackers through crafted PDF files, potentially exposing sensitive information from the process memory. The CVSS score of 5.5 indicates a medium risk, necessitating immediate attention from organizations using affected versions.

Risk to organizations includes unauthorized access to sensitive data, which can lead to further exploitation or data breaches. Given that exploitation is possible via crafted PDF files, it is crucial for defenders to prioritize patching to prevent potential data leaks. Organizations should update their systems to the latest version of Google Chrome to mitigate this risk.

As of now, there are no confirmed public exploits or known active exploitation of this vulnerability. However, the potential for exploitation exists, and organizations are urged to remain vigilant.

Organizations should prioritize patching immediately. Ensuring that all systems are updated will significantly reduce the risk of exploitation and protect sensitive information.

Vulnerability Details

The official description of CVE-2021-21219 states that uninitialized data in PDFium in Google Chrome prior to 90.0.4430.72 allowed a remote attacker to obtain potentially sensitive information from process memory via a crafted PDF file. This vulnerability has a CVSS 3.1 score of 5.5, indicating its medium severity level. The attack vector is considered local, with low complexity and no required privileges, but user interaction is necessary.

The confidentiality impact is high, while integrity and availability impacts are none. The vulnerability falls under CWE-252.

Technical Analysis

The root cause of this vulnerability is the presence of uninitialized data in the PDFium component of Google Chrome. Attackers may leverage this flaw by creating malicious PDF files that trigger the vulnerability when opened by users. The attack vector is local, meaning the attacker must have a means to deliver the crafted PDF file, typically requiring user interaction to open the file.

The attack complexity is low, and no privileges are required to exploit this vulnerability. However, user interaction is required, making it essential for users to be cautious when handling PDF files from untrusted sources.

The confidentiality impact of this vulnerability is high, as it may allow attackers to access sensitive data stored in memory. The integrity and availability impacts are assessed as none, indicating that while sensitive information could be exposed, the attack does not compromise the integrity or availability of the system.

Risk & Impact Analysis

The real-world risk associated with CVE-2021-21219 lies in its potential to expose sensitive information to unauthorized individuals. The blast radius for this vulnerability can be significant, especially in environments where users may inadvertently open malicious PDF files. Given the high confidentiality impact, organizations must consider the potential consequences of data exposure, which could lead to compliance violations or reputational damage.

Organizations should assess their environments for the presence of affected Google Chrome versions and prioritize updates. The urgency of this vulnerability, classified as medium severity, indicates that organizations should address it in their priority patch cycle to minimize risk exposure.

Considering the CVSS score and the potential for exploitation, organizations should remain vigilant and implement monitoring strategies to detect any unusual behavior related to PDF file handling.

Exploitation Status

Affected Versions

CVE-2021-21219 affects Google Chrome versions prior to 90.0.4430.72. Specifically, the vulnerable configurations include various versions of Chrome, Debian Linux 10.0, and multiple Fedora versions (32, 33, 34). Organizations should ensure all systems are updated to at least version 90.0.4430.72 to mitigate this vulnerability.

Mitigation & Remediation

Organizations are advised to apply patches and updates to all affected systems. The version to upgrade to is Google Chrome 90.0.4430.72 or later. If a patch is unavailable, consider implementing workarounds such as restricting access to untrusted PDF files and enhancing user training on identifying potentially harmful documents. Additionally, organizations should implement configuration hardening for their systems and maintain network controls to monitor and restrict PDF file handling.

For comprehensive security assessments, organizations may consider engaging in penetration testing to validate the effectiveness of their security measures.

Detection Guidance

To detect potential exploitation of this vulnerability, organizations should monitor logs for indicators of suspicious PDF file access or unusual memory access patterns. Behavioral anomalies in applications handling PDF files may also indicate attempts to exploit this vulnerability. It is essential to maintain updated antivirus solutions and enable logging for PDF viewer applications to aid in detection.

AppSecure Threat Intelligence Insight

CVE-2021-21219 reflects ongoing challenges in software security, particularly in the handling of uninitialized data. This vulnerability underscores the need for rigorous testing and validation of input data in software applications. Security teams should prioritize robust security practices and consider regular security assessments to identify similar vulnerabilities.

As a strategic defensive takeaway, organizations should incorporate lessons learned from this incident to enhance their application security frameworks. For further guidance on application security best practices, organizations may refer to resources such as the Application Security Assessment Guide, the Penetration Testing Methodology, and the Vulnerability Management Program Design to strengthen their overall security posture.