CVE-2020-23910 in asn1c
Summary
by MITRE • 07/18/2023
Stack-based buffer overflow vulnerability in asn1c through v0.9.28 via function genhash_get in genhash.c.
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Analysis
by VulDB Data Team • 08/09/2023
The CVE-2020-23910 vulnerability represents a critical stack-based buffer overflow flaw discovered in the asn1c tool version 0.9.28 and earlier. This vulnerability resides within the genhash.c source file and specifically affects the genhash_get function, making it a significant concern for systems that rely on ASN.1 compilation tools. The asn1c tool is widely used for generating C code from ASN.1 specifications, which are fundamental to telecommunications and networking protocols, including those used in 5G networks, internet protocols, and various enterprise communication systems. The vulnerability stems from improper bounds checking during hash table operations, where the function fails to validate input data length before copying it to a fixed-size stack buffer, creating an exploitable condition that can be leveraged by malicious actors to execute arbitrary code or cause system crashes.
The technical implementation of this vulnerability involves a classic stack buffer overflow scenario where the genhash_get function processes hash table entries without adequate input validation. When the function handles hash key data, it copies input values to a stack-allocated buffer without verifying that the source data length exceeds the buffer capacity. This flaw aligns with CWE-121, which describes stack-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent stack memory locations. The attack vector typically involves crafting malicious ASN.1 specifications that, when processed by the vulnerable asn1c tool, trigger the buffer overflow during compilation. The operational impact extends beyond simple code execution as it can compromise the integrity of the entire build process, potentially allowing attackers to inject malicious code into compiled applications or cause denial of service conditions that disrupt critical infrastructure operations.
The exploitation of CVE-2020-23910 has substantial operational implications for organizations relying on ASN.1-based systems, particularly in telecommunications, cybersecurity, and enterprise infrastructure domains. Attackers could leverage this vulnerability to compromise development environments where asn1c is used for generating protocol implementations, potentially leading to supply chain attacks or unauthorized access to sensitive network protocols. The vulnerability's presence in a widely-used ASN.1 compiler tool means that any system using asn1c to process untrusted ASN.1 specifications becomes a potential target. From an attack perspective, this flaw maps to several ATT&CK techniques including TA0002 (Execution) and TA0004 (Privilege Escalation) as successful exploitation could allow attackers to execute arbitrary code with the privileges of the build process. The impact is particularly severe in environments where automated builds process external or untrusted ASN.1 inputs, as these systems become vulnerable to remote code execution attacks that could compromise entire network infrastructures.
Organizations should prioritize immediate mitigation strategies including updating to asn1c version 0.9.29 or later, which contains the necessary patches to address the buffer overflow condition. Additionally, implementing input validation measures for ASN.1 specifications processed by the tool, including length restrictions and sanitization routines, can provide additional defense-in-depth. System administrators should also consider isolating the build environment from production networks and implementing strict access controls to limit who can execute the asn1c tool with potentially malicious inputs. The vulnerability demonstrates the importance of secure coding practices in development tools and highlights the need for regular security assessments of infrastructure components that are widely deployed across multiple systems. Organizations should also implement monitoring for unusual build activities and consider implementing static analysis tools to detect potential buffer overflow conditions in their own codebases that might interact with vulnerable components. This vulnerability serves as a reminder that even development tools can contain critical security flaws that can affect the entire software supply chain and require continuous vigilance and proactive security measures.