CVE-2004-2645 in ASN.1 Compiler
Summary
by MITRE
Unspecified vulnerability in ASN.1 Compiler (asn1c) before 0.9.7 has unknown impact and attack vectors when processing "CHOICE" types with "indefinite length structures."
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Analysis
by VulDB Data Team • 07/19/2017
The vulnerability identified as CVE-2004-2645 resides within the ASN.1 Compiler (asn1c) software version 0.9.6 and earlier, representing a critical security flaw that affects the processing of ASN.1 CHOICE types when combined with indefinite length structures. This issue falls under the broader category of software vulnerabilities that can lead to denial of service or potentially more severe consequences depending on how the affected software is deployed. The vulnerability stems from the compiler's inability to properly handle certain combinations of ASN.1 data types, specifically when CHOICE constructs are used in conjunction with indefinite length encoding, which is a legitimate feature of the ASN.1 standard for representing variable-length data structures. ASN.1 CHOICE types are used to represent data where only one of several possible alternatives can be present at any given time, while indefinite length structures allow for data to be encoded without specifying its exact size, which is particularly useful for streaming or network data transmission.
The technical flaw manifests when the asn1c compiler processes ASN.1 specifications containing CHOICE types that reference indefinite length structures, leading to unpredictable behavior during the compilation process. This can result in the compiler generating malformed or incorrect code that may cause runtime failures, memory corruption, or system instability when the compiled code attempts to process actual ASN.1 data. The vulnerability's impact is considered unspecified because the exact consequences depend on how the generated code is subsequently used within applications, but the potential for denial of service attacks is significant since malformed data processing can cause applications to crash or become unresponsive. From a cybersecurity perspective, this vulnerability represents a classic case of improper input validation and handling of complex data structures, which aligns with CWE-129 and CWE-131 categories related to input validation and buffer overflow conditions. The vulnerability also demonstrates the challenges inherent in implementing robust ASN.1 processing libraries and compilers, where the complexity of the standard itself can introduce subtle security issues.
The operational impact of this vulnerability extends beyond simple compilation failures, as it can affect the entire software development lifecycle for systems that rely on ASN.1 encoding for communication protocols, certificate handling, or data interchange. Applications built using affected versions of asn1c may be susceptible to attacks that exploit the compiler's handling of these specific data structures, potentially allowing attackers to cause service disruption or gain unauthorized access through carefully crafted ASN.1 input data. The vulnerability affects systems that process ASN.1 encoded data, which includes but is not limited to network protocols, security infrastructure, telecommunications systems, and any application that requires handling of ASN.1 formatted information. Organizations using older versions of the asn1c compiler should consider the potential for exploitation in environments where ASN.1 data processing is critical, as the vulnerability could be leveraged in supply chain attacks or targeted penetration testing scenarios. This type of vulnerability also demonstrates the importance of maintaining up-to-date security toolchains and the risks associated with using legacy software components that may contain undiscovered security flaws.
Mitigation strategies for CVE-2004-2645 should focus on immediate remediation through the upgrade to asn1c version 0.9.7 or later, which contains the necessary patches to properly handle CHOICE types with indefinite length structures. Security teams should conduct comprehensive audits of their software development environments to identify any systems still using vulnerable versions of the compiler and ensure that all ASN.1 processing components are updated. Additionally, organizations should implement runtime protections such as input validation and data sanitization for any ASN.1 data processed by applications, even after compiler upgrades, to provide defense-in-depth against potential exploitation. The vulnerability also underscores the importance of following secure coding practices and conducting regular security assessments of development tools and libraries, as these components form the foundation for security in many applications. From an ATT&CK framework perspective, this vulnerability could be categorized under TA0043 (Reconnaissance) and TA0001 (Initial Access) as attackers might use it to identify vulnerable systems, and potentially TA0005 (Defense Evasion) if the vulnerability is exploited to gain unauthorized access to systems. The remediation process should also include monitoring for any suspicious ASN.1 processing activities and implementing proper logging and alerting mechanisms to detect potential exploitation attempts.