CVE-2006-0898 in Perl
Summary
by MITRE
Crypt::CBC Perl module 2.16 and earlier, when running in RandomIV mode, uses an initialization vector (IV) of 8 bytes, which results in weaker encryption when used with a cipher that requires a larger block size than 8 bytes, such as Rijndael.
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Analysis
by VulDB Data Team • 06/15/2019
The Crypt::CBC Perl module vulnerability CVE-2006-0898 represents a significant cryptographic weakness that undermines the security of encrypted data when using certain cipher modes. This flaw specifically affects versions 2.16 and earlier of the module, which is commonly used in Perl applications for implementing cipher block chaining encryption. The vulnerability stems from the module's improper handling of initialization vectors in RandomIV mode, creating a fundamental mismatch between the IV size and the cryptographic requirements of modern ciphers. When the module operates with ciphers like Rijndael that require block sizes larger than 8 bytes, the 8-byte IV becomes insufficient for maintaining proper cryptographic security.
The technical flaw manifests when the Crypt::CBC module generates an 8-byte initialization vector for encryption operations, despite the underlying cipher requiring a larger block size for secure operation. This creates a predictable pattern in the encryption process that weakens the overall cryptographic strength. The vulnerability specifically impacts the RandomIV mode where the module should generate a cryptographically secure IV of appropriate length for the selected cipher algorithm. However, due to the hardcoded 8-byte limit, the encryption becomes susceptible to various cryptographic attacks that exploit the reduced entropy and predictable IV patterns. The flaw violates the fundamental cryptographic principle that initialization vectors must be of sufficient length to ensure proper diffusion and resistance to pattern analysis attacks.
The operational impact of this vulnerability extends beyond simple data confidentiality concerns, affecting the integrity and security posture of systems relying on the Crypt::CBC module for encryption. Applications using affected versions may experience reduced encryption strength that could be exploited by adversaries to perform statistical analysis, pattern recognition, or even partial decryption of encrypted data. The weakness becomes particularly pronounced when dealing with modern encryption standards that require larger block sizes to maintain security margins, as the 8-byte IV fails to provide adequate entropy for ciphers with 16-byte or larger block sizes. This vulnerability affects a broad range of Perl applications including web applications, database encryption systems, and network security tools that depend on the module for secure data handling operations.
Mitigation strategies for this vulnerability require immediate updates to the Crypt::CBC module to versions that properly handle initialization vectors according to cryptographic best practices. System administrators should prioritize patching affected systems and conducting thorough inventory checks to identify all applications using vulnerable versions of the module. The remediation process involves upgrading to Crypt::CBC versions that implement proper IV generation mechanisms consistent with the cipher block sizes being used, typically requiring IVs that match or exceed the cipher's block size requirements. Organizations should also consider implementing additional monitoring and logging mechanisms to detect potential exploitation attempts and maintain audit trails of encryption operations. Security teams should review their cryptographic implementations and ensure compliance with industry standards such as those outlined in the CWE database under category 310 for cryptographic weaknesses, and consider mapping this vulnerability to ATT&CK techniques related to credential access and defense evasion through cryptographic manipulation.