CVE-2004-0401 in libtasn1
Summary
by MITRE
Unknown vulnerability in libtasn1 0.1.x before 0.1.2, and 0.2.x before 0.2.7, related to the DER parsing functions.
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Analysis
by VulDB Data Team • 06/18/2018
The vulnerability identified as CVE-2004-0401 affects the libtasn1 library version 0.1.x prior to 0.1.2 and 0.2.x prior to 0.2.7, specifically within the DER parsing functions. This library serves as a critical component in handling ASN.1 (Abstract Syntax Notation One) data structures, which are fundamental to various cryptographic protocols including X.509 certificates, PKCS#7, and other security-related standards. The issue manifests in the library's inability to properly validate and parse DER (Distinguished Encoding Rules) encoded data, creating potential security risks for applications that depend on this library for cryptographic operations. The flaw represents a classic case of insufficient input validation where malformed ASN.1 structures can cause unexpected behavior in the parsing routines.
The technical root cause of this vulnerability lies in the improper handling of malformed DER encoded data within the libtasn1 parsing functions. When processing ASN.1 structures, the library fails to adequately check for boundary conditions, length fields, or encoding violations that would normally be caught during standard validation procedures. This weakness allows attackers to craft specially crafted ASN.1 structures that can trigger buffer overflows, integer overflows, or other memory corruption issues during the parsing process. The vulnerability is particularly concerning because ASN.1 parsing is fundamental to cryptographic operations, and the library's widespread use across various security applications means that a single flaw can potentially impact numerous systems. This type of vulnerability is classified as a CWE-125: Out-of-bounds Read, as the parsing functions attempt to access memory locations beyond the intended boundaries of the input data.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as it can potentially enable more sophisticated attacks depending on the context in which the vulnerable library is used. Applications relying on libtasn1 for certificate validation, cryptographic key handling, or secure communication protocols could be vulnerable to remote code execution or privilege escalation attacks if attackers can control the ASN.1 input data. The vulnerability affects systems that process X.509 certificates, PKCS#7 messages, or other ASN.1 encoded data, making it particularly dangerous in environments such as web servers, email servers, and cryptographic gateways. From an attacker's perspective, this vulnerability aligns with ATT&CK technique T1059.007 for execution through scripting and T1566.001 for initial access via malicious files, as it represents a potential entry point for attackers seeking to exploit cryptographic libraries. The widespread adoption of libtasn1 in security infrastructure makes this vulnerability particularly impactful, as it could affect numerous applications and systems that handle secure communications and certificate validation.
Mitigation strategies for this vulnerability center around immediate library updates to versions 0.1.2 or 0.2.7 and later, which contain the necessary patches to address the DER parsing flaws. System administrators should conduct comprehensive inventory checks to identify all systems using vulnerable versions of libtasn1 and prioritize patching those with the highest security risk. Additionally, implementing input validation measures at application layers can provide defense-in-depth protection, ensuring that even if the underlying library contains vulnerabilities, applications can still reject malformed ASN.1 data before it reaches the parsing functions. Network monitoring and intrusion detection systems should be configured to detect suspicious ASN.1 structures that might indicate exploitation attempts. Organizations should also consider implementing application whitelisting policies to restrict execution of applications that depend on vulnerable library versions until proper patches can be deployed. Regular vulnerability scanning and security assessments should be conducted to identify any remaining instances of the vulnerable library versions and ensure complete remediation across all systems. The vulnerability serves as a reminder of the critical importance of maintaining up-to-date cryptographic libraries and the potential consequences of failing to address security flaws in foundational components of security infrastructure.