CVE-2022-1934 in mruby
Summary
by MITRE • 05/31/2022
Use After Free in GitHub repository mruby/mruby prior to 3.2.
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Analysis
by VulDB Data Team • 06/04/2022
The vulnerability identified as CVE-2022-1934 represents a critical use-after-free flaw in the mruby interpreter library that affects versions prior to 3.2. This issue resides within the mruby repository hosted on GitHub and demonstrates a fundamental memory safety problem that can lead to arbitrary code execution. The vulnerability stems from improper memory management practices where freed memory blocks are still being referenced or accessed by subsequent operations. Such flaws typically occur when the interpreter fails to properly track object lifetimes and maintain consistent memory references throughout program execution. The specific conditions that trigger this vulnerability involve scenarios where mruby's garbage collection mechanism interacts improperly with object reference counting, creating opportunities for attackers to manipulate memory state.
The technical implementation of this use-after-free vulnerability manifests when the mruby interpreter processes certain Ruby code patterns that involve object destruction and subsequent reference operations. The flaw occurs during the execution of methods that manipulate object references, particularly in contexts involving nested object creation and destruction sequences. When an object is freed from memory but references to it persist in other parts of the interpreter's internal data structures, attackers can exploit this condition to overwrite memory locations with malicious payloads. This memory corruption can occur through carefully crafted input that triggers specific code paths within the mruby interpreter, allowing for potential privilege escalation or complete system compromise. The vulnerability aligns with CWE-416, which specifically addresses use-after-free conditions in memory management, and represents a classic example of how improper reference counting can lead to exploitable memory corruption.
The operational impact of CVE-2022-1934 extends beyond simple memory corruption, as it can enable attackers to execute arbitrary code with the privileges of the mruby process. This capability provides potential access to sensitive data, system resources, and can serve as a foothold for further attacks within compromised environments. Systems utilizing mruby as a scripting engine or embedded interpreter are particularly vulnerable, including web applications, embedded systems, and development tools that depend on mruby for execution. The vulnerability's exploitation potential is heightened when mruby is used in environments where untrusted input is processed, as attackers can craft malicious Ruby code to trigger the memory corruption. This represents a significant concern for security teams as it can be leveraged to bypass security controls, escalate privileges, and establish persistent access to affected systems. The ATT&CK framework categorizes this vulnerability under the T1059.007 technique for 'Command and Scripting Interpreter: mruby' and T1068 for 'Exploitation for Privilege Escalation' when properly leveraged by attackers.
Mitigation strategies for CVE-2022-1934 primarily focus on immediate remediation through version upgrades to mruby 3.2 or later, which contain the necessary memory management fixes. Organizations should conduct comprehensive inventory assessments to identify all systems utilizing vulnerable mruby versions and prioritize patching efforts accordingly. Additionally, implementing runtime protections such as address space layout randomization and stack canaries can help mitigate exploitation attempts. Input validation and sanitization measures should be strengthened to prevent malicious code injection into mruby environments, while monitoring systems should be enhanced to detect anomalous behavior patterns that may indicate exploitation attempts. Security teams should also consider implementing network segmentation and access controls to limit the potential impact of successful exploitation, particularly in environments where mruby is used in critical system components or web-facing applications. Regular security assessments and penetration testing should be conducted to verify the effectiveness of implemented mitigations and identify any additional vulnerabilities in related systems that may leverage mruby components.