CVE-2021-21289 is a high-severity command injection vulnerability affecting the Mechanize library, an open-source Ruby tool for automating web interactions. The vulnerability exists in versions from 2.0.0 up to, but not including, 2.7.7. Specifically, it allows attackers to inject operating system commands through methods that implicitly utilize Ruby's Kernel.open method. Exploitation occurs when untrusted input is passed as a local filename to certain methods, including Mechanize::CookieJar#load, Mechanize::CookieJar#save_as, Mechanize#download, Mechanize::Download#save, Mechanize::File#save, and Mechanize::FileResponse#read_body.
The CVSS score for this vulnerability is 7.4, classified as high severity. This score reflects the potential impact of a successful attack, which could lead to significant integrity issues. The vulnerability's attack vector is network-based, and the complexity is low, indicating that successful exploitation could be relatively easy for an attacker with access to untrusted input.
Organizations utilizing affected versions of Mechanize are at risk of command injection attacks, which can result in unauthorized command execution on the server. This risk necessitates immediate action and remediation. The library has been patched in version 2.7.7, and organizations are strongly encouraged to update to this version or later to mitigate the risk.
Given the potential impact of this vulnerability, organizations should prioritize patching Mechanize immediately. Failure to do so may expose systems to exploitation and data compromise.
Vulnerability Details
The official CVE description indicates that this vulnerability allows for OS commands to be injected. The affected versions of Mechanize range from 2.0.0 to 2.7.7, and the vulnerability is classified under CWE-78, which involves command injection. The CVSS score is derived from factors such as attack vector, complexity, and required privileges, emphasizing the need for organizations to assess their exposure.
Technical Analysis
The root cause of CVE-2021-21289 lies in how the Mechanize library handles untrusted inputs and passes them to Ruby's Kernel.open method. Attackers may exploit this vulnerability by sending crafted input that gets executed as a command. The attack vector is network-based, allowing remote attackers to trigger the vulnerability. The attack complexity is rated as low, which means minimal effort is required to exploit the vulnerability.
This vulnerability does not require any privileges, making it accessible to unauthenticated attackers. User interaction is required, as the attacker must trick the user into providing untrusted input that is processed by the vulnerable methods. The confidentiality impact is rated as none, but the integrity impact is rated as high due to the potential for unauthorized command execution.
Availability impact is rated as none, indicating that the vulnerability does not directly affect the availability of the system. Overall, the technical details underscore the importance of validating user input to prevent command injection attacks.
Risk & Impact Analysis
The risk to organizations includes the possibility of unauthorized execution of commands on affected systems, which may lead to data breaches and system compromise. The blast radius could extend to any organization using affected versions of Mechanize, particularly those that handle sensitive data or operate in regulated environments. Given the high CVSS score, organizations must assess their exposure and the potential impact on their operations.
Urgency for remediation is high, given the nature of the vulnerability and the potential for exploitation. Organizations should address this vulnerability in their priority patch cycle to mitigate the risk of exploitation.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The affected versions of Mechanize are from 2.0.0 to 2.7.6. Organizations should upgrade to version 2.7.7 or later to secure their applications. Other affected products include Fedora versions 32 and 33, and Debian version 9.0.
Mitigation & Remediation
To mitigate the risks associated with CVE-2021-21289, organizations should immediately update Mechanize to version 2.7.7 or later. If upgrading is not feasible, consider implementing input validation mechanisms to ensure that untrusted input is not processed as local filenames.
Network controls should also be reviewed to limit access to vulnerable systems. Continuous monitoring for unusual activity may help in early detection of exploitation attempts.
For additional support, organizations can utilize penetration testing services to validate their security posture.
Detection Guidance
Organizations should monitor logs for indicators of unusual command execution patterns. Look for behavioral anomalies in application usage that may suggest exploitation attempts, such as unexpected calls to the vulnerable methods.
Establish network signatures to detect attempts to exploit this vulnerability, focusing on traffic patterns that deviate from normal operations.
AppSecure Threat Intelligence Insight
The long-term significance of CVE-2021-21289 lies in the increasing trend of command injection vulnerabilities in widely used libraries. This case highlights the necessity for security teams to implement robust input validation strategies to mitigate potential exploitation.
Organizations should regularly audit their libraries and frameworks for known vulnerabilities. The patching process should be integrated into the software development lifecycle to ensure timely remediation of such vulnerabilities.
For further reading on related topics, organizations can refer to our vulnerability management program and explore our comprehensive penetration testing methodology resources.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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