CVE-2003-0545 in OpenSSL
Summary
by MITRE
Double free vulnerability in OpenSSL 0.9.7 allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via an SSL client certificate with a certain invalid ASN.1 encoding.
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Analysis
by VulDB Data Team • 12/26/2024
The vulnerability described in CVE-2003-0545 represents a critical double free error within the OpenSSL 0.9.7 implementation that fundamentally compromises the security and stability of SSL/TLS communications. This issue arises from improper memory management during the processing of X509 certificate structures, specifically when handling malformed ASN.1 encoded client certificates. The flaw exists in the X509_NAME_print_ex function within the OpenSSL library, where the application fails to properly validate certificate structures before attempting memory operations. When an attacker submits a specially crafted SSL client certificate containing invalid ASN.1 encoding, the vulnerable code path executes multiple free operations on the same memory block, leading to unpredictable behavior and potential exploitation.
The technical nature of this vulnerability aligns with CWE-415, which describes double free conditions in memory management, and can be categorized under the broader ATT&CK technique T1059.007 for command and scripting interpreter. The memory corruption resulting from this double free creates opportunities for remote code execution through heap-based memory corruption attacks, where attackers can manipulate the freed memory to overwrite critical program structures or inject malicious code. The vulnerability specifically impacts the X509_NAME_print_ex function within OpenSSL's certificate parsing routines, where the library attempts to process certificate subject names without adequate validation of the underlying ASN.1 structure, leading to the repeated deallocation of memory segments.
Operationally, this vulnerability presents a significant risk to any system running OpenSSL 0.9.7 that accepts SSL client certificates, including web servers, email servers, and any SSL/TLS services that authenticate clients. The remote exploitation capability means that attackers can trigger the vulnerability without requiring local access, making it particularly dangerous for publicly exposed services. The denial of service component causes immediate service disruption through application crashes, while the potential for arbitrary code execution creates long-term security implications. Systems that process client certificates for authentication purposes are particularly vulnerable, as attackers can craft malicious certificates to exploit this weakness and potentially gain elevated privileges on the target system.
Mitigation strategies for CVE-2003-0545 require immediate patching of affected OpenSSL installations to version 0.9.7a or later, which contains the necessary memory management fixes. Organizations should implement certificate validation policies that reject malformed certificates at the network level using intrusion detection systems or firewalls that can identify and block suspicious ASN.1 structures. Network segmentation and monitoring of SSL/TLS traffic can help detect exploitation attempts before they succeed. Additionally, system administrators should disable unnecessary SSL client certificate authentication where possible and implement proper certificate revocation checking. The vulnerability demonstrates the critical importance of proper input validation and memory management in cryptographic libraries, as highlighted by security frameworks such as the OWASP Top Ten and NIST Cybersecurity Framework, which emphasize the need for robust validation of all input data before processing.