CVE-2020-27795 in radare2
Summary
by MITRE • 08/20/2022
A segmentation fault was discovered in radare2 with adf command. In libr/core/cmd_anal.c, when command "adf" has no or wrong argument, anal_fcn_data (core, input + 1) --> RAnalFunction *fcn = r_anal_get_fcn_in (core->anal, core->offset, -1); returns null pointer for fcn causing segmentation fault later in ensure_fcn_range (fcn).
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Analysis
by VulDB Data Team • 09/24/2022
The vulnerability CVE-2020-27795 represents a critical null pointer dereference issue within the radare2 reverse engineering framework, specifically affecting the adf command implementation. This flaw exists in the libr/core/cmd_anal.c file where the analysis command processing fails to properly validate input arguments before proceeding with function analysis operations. The root cause stems from the anal_fcn_data function which attempts to retrieve a function analysis object using r_anal_get_fcn_in() without first verifying that the returned pointer is valid, leading to a segmentation fault when subsequent operations attempt to access the null pointer.
The technical execution of this vulnerability occurs when users invoke the adf command with either no arguments or incorrect argument formats, triggering the problematic code path where core->anal is queried for function information at the current offset. The r_anal_get_fcn_in() function returns a null pointer when it cannot locate an existing function at the specified address, but the calling code does not perform proper null pointer checks before proceeding. This null pointer is then passed to ensure_fcn_range() function which attempts to dereference the null pointer, resulting in an immediate segmentation fault that crashes the radare2 application.
From an operational perspective, this vulnerability presents a significant risk to security researchers and analysts who rely on radare2 for malware analysis, binary reverse engineering, and security assessments. The segmentation fault can be exploited by malicious actors to cause denial of service attacks against systems running radare2, potentially disrupting critical security analysis workflows. The vulnerability affects the core analysis functionality of the tool, making it particularly dangerous as it can prevent legitimate users from performing essential reverse engineering tasks. According to CWE classification, this corresponds to CWE-476 Null Pointer Dereference, which is a well-known weakness pattern that leads to application crashes and potential information disclosure.
The impact extends beyond simple application crashes as this vulnerability can be leveraged in broader attack scenarios within the context of the ATT&CK framework. Specifically, it relates to the T1059 Command and Scripting Interpreter technique where adversaries might attempt to exploit command-line interface vulnerabilities. The flaw also connects to T1588 Defense Evasion tactics as attackers could potentially use this vulnerability to disrupt security analysis processes. Additionally, the vulnerability affects the T1068 Exploitation for Privilege Escalation category when considering potential escalation paths through compromised analysis environments.
Mitigation strategies for CVE-2020-27795 should prioritize immediate patch application from the radare2 development team, as this represents a critical security issue requiring urgent attention. System administrators and security analysts should implement input validation controls and parameter sanitization when using radare2 in automated analysis workflows. The recommended approach involves adding proper null pointer checks in the affected code path, specifically ensuring that the return value from r_anal_get_fcn_in() is validated before proceeding with subsequent operations. Organizations should also consider implementing runtime monitoring for segmentation fault occurrences and establishing robust error handling mechanisms within their reverse engineering environments. The fix should include defensive programming practices that align with secure coding guidelines and prevent similar null pointer dereference issues throughout the codebase.