CVE-2021-32495 in Radare2
Summary
by MITRE • 07/07/2023
Radare2 has a use-after-free vulnerability in pyc parser's get_none_object function. Attacker can read freed memory afterwards. This will allow attackers to cause denial of service.
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Analysis
by VulDB Data Team • 07/25/2023
The vulnerability identified as CVE-2021-32495 represents a critical use-after-free condition within the radare2 binary analysis framework, specifically affecting the python bytecode parser component. This flaw exists in the get_none_object function of the pyc parser module, where improper memory management allows attackers to manipulate freed memory locations. The issue manifests when the parser processes python bytecode files, creating a scenario where memory allocated to objects is deallocated but subsequently accessed, leading to unpredictable behavior and potential exploitation.
The technical nature of this vulnerability aligns with CWE-416, which classifies use-after-free conditions as a fundamental memory safety issue. When the pyc parser encounters specific bytecode patterns, it triggers the get_none_object function which frees memory associated with python None objects. However, the subsequent code execution path fails to properly validate that the memory has not been reallocated or overwritten, creating opportunities for attackers to read from freed memory locations. This memory access pattern can reveal sensitive information stored in adjacent memory regions or potentially allow for more sophisticated exploitation techniques.
From an operational impact perspective, this vulnerability enables attackers to execute denial of service attacks against systems running radare2 with maliciously crafted python bytecode files. The use-after-free condition can cause application crashes, leading to service unavailability for legitimate users. In more advanced exploitation scenarios, the memory read access could potentially expose stack contents, heap metadata, or other sensitive data that might aid in further exploitation attempts. The vulnerability affects radare2 versions prior to 5.0.0, making it particularly concerning for security researchers and analysts who rely on this tool for malware analysis and reverse engineering activities.
The ATT&CK framework categorizes this vulnerability under T1499.004, which covers the use of memory corruption techniques for system disruption. Attackers could leverage this weakness to disrupt security analysis workflows where radare2 is employed, particularly in environments where automated analysis systems process untrusted python bytecode. Mitigation strategies should focus on immediate patching to version 5.0.0 or later where the memory management issues have been resolved. Additionally, organizations should implement proper input validation and sandboxing measures when processing python bytecode files, particularly in automated analysis environments where untrusted content is regularly encountered. The vulnerability demonstrates the critical importance of memory safety in security tools, as flaws in analysis frameworks can potentially compromise the integrity of security research and analysis operations.