This vulnerability allows attackers to inject arbitrary Java EL expressions through template injection in cron-utils, which may lead to unauthenticated Remote Code Execution (RCE). The severity of this vulnerability is critical, with a CVSS score of 10.0, indicating an urgent need for remediation. Affected versions include all prior to 9.1.6, and organizations must prioritize patching immediately to prevent exploitation.
Risk to organizations includes unauthorized execution of code, resulting in potential data breaches, data loss, or compromise of system integrity. Given the nature of this vulnerability, the attack vector is identified as network-based, with low complexity and no required privileges or user interaction, making it particularly dangerous.
Currently, there is no public exploit confirmed for this vulnerability, and it has not been included in the Known Exploited Vulnerabilities (KEV) catalog. However, the presence of a proof of concept on GitHub raises concerns about the potential for exploitation in the wild.
Organizations should assess their use of cron-utils and ensure they upgrade to version 9.1.6 or later as part of their immediate patch management process. This proactive step is crucial to maintaining the security of their systems and data.
Vulnerability Details
The CVE-2021-41269 vulnerability was identified in cron-utils, a Java library that facilitates the definition, parsing, and validation of cron expressions. Specifically, a template injection vulnerability allows attackers to submit arbitrary Java EL expressions which can lead to unauthorized remote code execution.
The official description indicates that only projects utilizing the @Cron annotation for validating untrusted cron expressions are affected. The vulnerability affects versions up to 9.1.2, and a patch has been released in version 9.1.6.
The CVSS score for this vulnerability is 10, categorized as critical. It reflects high potential impact across confidentiality, integrity, and availability due to the nature of the vulnerability.
The vulnerability is classified under CWE-94, indicating a code injection issue. Organizations should ensure their systems are not vulnerable to such injection attacks.
Technical Analysis
The root cause of this vulnerability lies in the improper validation of user input within cron-utils. Specifically, the library allows for the injection of Java EL expressions, which can be executed without proper authentication checks, leading to a remote code execution scenario.
The attack vector is network-based, where an attacker can exploit the vulnerability remotely without requiring physical access to the system. The attack complexity is low, meaning that a potential attacker does not need advanced skills to exploit this vulnerability. No privileges are required to execute the attack, and user interaction is not necessary, making exploitation straightforward.
The confidentiality impact is rated high, as unauthorized access to sensitive data may occur. Similarly, the integrity and availability impacts are also high, given the potential for attackers to execute arbitrary code, which could compromise system functionality or alter data.
Risk & Impact Analysis
Organizations utilizing cron-utils must recognize the real-world deployment risks associated with this vulnerability. Given its critical nature, the potential blast radius is significant, especially for systems that are exposed to the internet or other untrusted networks.
The urgency assessment is critical, as the CVSS score of 10 indicates that exploitation can lead to severe consequences, including data breaches and unauthorized control over affected systems. Organizations should prioritize patching this vulnerability immediately to mitigate risks.
The potential for exploitation raises concerns not only for the affected organizations but also for their clients and stakeholders, as unauthorized access could lead to data leaks or operational disruptions.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | Yes |
Public PoC | Yes |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
All versions prior to 9.1.6 of cron-utils are affected by this vulnerability. Organizations are advised to upgrade to the latest version to mitigate the risk of exploitation.
Mitigation & Remediation
To remediate this vulnerability, organizations should upgrade to cron-utils version 9.1.6 or later. This patch addresses the template injection vulnerability and prevents unauthorized code execution.
If immediate patching is not feasible, organizations should implement strict input validation and avoid using the @Cron annotation for untrusted expressions until an upgrade can be performed. Continuous security testing practices, such as continuous penetration testing, should be employed to identify and remediate potential vulnerabilities.
Monitoring for unusual behavior and implementing network controls to restrict access to affected systems are also recommended to reduce the risk of exploitation.
Detection Guidance
Organizations should implement logging mechanisms to capture any anomalies related to cron job executions. This includes monitoring for unexpected changes to cron expressions or unauthorized access attempts to cron-utils functionality.
Behavioral anomalies, such as unusual execution patterns of scheduled jobs, should be investigated. Network signatures that correlate with cron-utils API calls should be established to detect potential exploitation attempts.
Regular audits of cron job configurations and closely monitoring system changes can help identify any signs of compromise or exploitation.
AppSecure Threat Intelligence Insight
The long-term significance of CVE-2021-41269 lies in its demonstration of the risks associated with improper input validation in software libraries. As organizations increasingly rely on automated task scheduling, the potential for such vulnerabilities to be exploited remains a concern.
This vulnerability highlights the need for security teams to adopt a holistic approach to application security, incorporating rigorous testing and validation processes during development. Security teams should also be aware of the patterns and trends in vulnerabilities related to code injection and remote execution.
Continuous learning from incidents, such as this one, can strengthen defenses against similar vulnerabilities in the future. Organizations should integrate findings from vulnerabilities like this into their overall security posture and response strategies.
For more insights on managing application security, organizations can explore our resources on vulnerability management programs, penetration testing methodologies, and security testing best practices to strengthen defenses.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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