CVE-2002-0703 in Digest-md5
Summary
by MITRE
An interaction between the Perl MD5 module (perl-Digest-MD5) and Perl could produce incorrect MD5 checksums for UTF-8 data, which could prevent a system from properly verifying the integrity of the data.
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Analysis
by VulDB Data Team • 06/27/2021
The vulnerability described in CVE-2002-0703 represents a critical cryptographic flaw in the perl-Digest-MD5 module that affected systems relying on MD5 checksums for data integrity verification. This issue emerged from the interaction between the Perl programming language and its cryptographic modules, specifically demonstrating how language-level implementation details could compromise security mechanisms. The vulnerability was particularly concerning because MD5 checksums are fundamental to ensuring data integrity across numerous applications and systems, making this flaw potentially widespread in its impact. The flaw specifically manifested when processing UTF-8 encoded data, which is standard in modern text processing and internationalized applications.
The technical root cause of this vulnerability lies in how the perl-Digest-MD5 module handled character encoding during MD5 computation for UTF-8 data. When Perl processes UTF-8 encoded strings, it performs internal character set conversions that can interfere with the MD5 hashing algorithm's expected input format. This interaction resulted in incorrect MD5 checksum calculations where the computed hash values did not match the expected cryptographic output for the same input data. The flaw was classified as a weakness in cryptographic implementation, aligning with CWE-327 which addresses the use of weak or broken cryptographic algorithms and improper implementation of cryptographic functions. The vulnerability essentially created a scenario where systems could not reliably verify data integrity, potentially allowing malicious actors to manipulate data without detection.
The operational impact of this vulnerability extended far beyond simple checksum failures, as it undermined fundamental security assumptions in systems relying on MD5 verification. Applications that depended on MD5 for file integrity checks, software distribution verification, or data transmission validation could be compromised, potentially allowing attackers to substitute malicious content while maintaining valid MD5 checksums. This weakness created a false sense of security in systems where data integrity was paramount, such as software package distribution systems, backup verification processes, and cryptographic protocol implementations. The vulnerability particularly affected systems where UTF-8 text processing was common, making it relevant to web applications, internationalized software, and any system handling Unicode text. From an attacker's perspective, this flaw aligned with ATT&CK technique T1027 which involves obfuscation and manipulation of data integrity mechanisms, potentially enabling more sophisticated attacks.
Mitigation strategies for CVE-2002-0703 required immediate updates to the perl-Digest-MD5 module and affected Perl installations. System administrators needed to apply patches that corrected the character encoding handling during MD5 computation, ensuring that UTF-8 data was processed correctly without interfering with cryptographic functions. Organizations should have implemented comprehensive testing procedures to verify that MD5 checksums were functioning correctly after patching, particularly for systems handling internationalized text. The vulnerability highlighted the importance of thorough testing of cryptographic implementations under various data encoding scenarios and underscored the need for careful attention to language-specific behavior in security-critical applications. Additionally, this incident reinforced the broader principle that cryptographic implementations must be rigorously tested against edge cases and various input formats to prevent similar vulnerabilities in the future.