CVE-2018-20459 in radare2
Summary
by MITRE
In radare2 through 3.1.3, the armass_assemble function in libr/asm/arch/arm/armass.c allows attackers to cause a denial-of-service (application crash by out-of-bounds read) by crafting an arm assembly input because a loop uses an incorrect index in armass.c and certain length validation is missing in armass64.c, a related issue to CVE-2018-20457.
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Analysis
by VulDB Data Team • 06/22/2023
The vulnerability identified as CVE-2018-20459 represents a critical denial-of-service flaw affecting radare2 versions through 3.1.3, specifically within the ARM assembly processing functionality. This issue stems from improper memory handling in the armass_assemble function located in libr/asm/arch/arm/armass.c, where attackers can manipulate the application into crashing through carefully crafted ARM assembly input. The root cause manifests as an out-of-bounds read condition that occurs when a loop utilizes an incorrect index value, effectively allowing malicious input to traverse memory regions beyond intended boundaries.
The technical implementation of this vulnerability involves two primary components that together create the exploitable condition. First, the armass.c file contains a loop structure that fails to properly validate array indices, leading to memory access violations when processing malformed ARM assembly instructions. Second, the armass64.c file lacks adequate length validation mechanisms, creating additional attack surface that compounds the memory safety issue. These flaws collectively enable an attacker to construct specific assembly input that triggers the application crash, making this vulnerability particularly dangerous in environments where radare2 is used for binary analysis or reverse engineering tasks.
From an operational perspective, this vulnerability poses significant risks to security researchers and analysts who rely on radare2 for their work. The denial-of-service condition can disrupt critical analysis workflows, potentially causing analysts to lose unsaved work or interrupt ongoing reverse engineering processes. The vulnerability's impact extends beyond simple application instability, as it could be exploited in automated testing environments or security tools that depend on radare2's assembly capabilities. Given that radare2 is widely used in penetration testing, malware analysis, and software security research, the potential for cascading effects in security operations is considerable.
The vulnerability aligns with CWE-129, which addresses improper validation of array index values, and represents a specific instance of out-of-bounds memory access. From an ATT&CK framework perspective, this issue could be leveraged as part of a broader reconnaissance or preparation phase in an attack lifecycle, where adversaries might attempt to disrupt security analysis tools before conducting more sophisticated operations. The vulnerability's relationship to CVE-2018-20457 indicates that it forms part of a larger family of ARM assembly processing flaws within radare2, suggesting potential for additional related vulnerabilities that security teams should consider when assessing their radare2 implementations. Organizations using radare2 should prioritize updating to versions that address these assembly processing flaws to prevent potential exploitation that could compromise their security analysis capabilities.
Mitigation strategies should focus on immediate version updates to radare2 releases that contain fixes for both the index validation issues in armass.c and the length validation deficiencies in armass64.c. Security teams should also implement monitoring for suspicious assembly input patterns that might indicate attempts to exploit this vulnerability. Additionally, defensive coding practices should be reinforced throughout development teams working with similar assembly processing libraries to prevent similar out-of-bounds read conditions from occurring in other security tools. The vulnerability serves as a reminder of the critical importance of memory safety validation in security tools, particularly those handling user-provided input in low-level processing functions.