CVE-2017-12871 in SimpleSAMLphp
Summary
by MITRE
The aesEncrypt method in lib/SimpleSAML/Utils/Crypto.php in SimpleSAMLphp 1.14.x through 1.14.11 makes it easier for context-dependent attackers to bypass the encryption protection mechanism by leveraging use of the first 16 bytes of the secret key as the initialization vector (IV).
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Analysis
by VulDB Data Team • 12/27/2022
The vulnerability identified as CVE-2017-12871 resides within the SimpleSAMLphp authentication framework, specifically in the cryptographic implementation found in the lib/SimpleSAML/Utils/Crypto.php file. This issue affects versions 1.14.x through 1.14.11, representing a significant security flaw that undermines the integrity of the encryption mechanism. The vulnerability stems from a flawed approach to cryptographic key usage where the system employs the initial 16 bytes of the secret key as the initialization vector for encryption operations, creating a predictable and potentially exploitable pattern.
The technical flaw manifests when the aesEncrypt method processes data encryption, where the cryptographic implementation fails to properly randomize the initialization vector. This design decision violates fundamental cryptographic principles by creating a deterministic encryption process where the same plaintext will produce the same ciphertext when encrypted with the same key. The vulnerability falls under CWE-327, which addresses the use of insecure or weak cryptographic algorithms, and specifically relates to improper key usage patterns that compromise encryption security. The predictable IV usage creates a scenario where attackers can potentially perform statistical analysis on encrypted communications to infer information about the plaintext content.
The operational impact of this vulnerability extends beyond simple encryption bypass, creating potential attack vectors for context-dependent adversaries who can exploit the predictable encryption patterns. Attackers can leverage this weakness to perform man-in-the-middle attacks, decrypt intercepted communications, or conduct traffic analysis that would normally be prevented by proper encryption. The vulnerability is particularly dangerous in authentication contexts where SimpleSAMLphp is used, as it could allow attackers to compromise authentication tokens, session data, or other sensitive information exchanged during the authentication process. This weakness directly impacts the confidentiality and integrity guarantees that cryptographic systems are designed to provide.
Mitigation strategies for CVE-2017-12871 require immediate patching of affected SimpleSAMLphp installations to versions that properly implement cryptographic key usage patterns. Organizations should ensure that all instances of SimpleSAMLphp are updated to versions that generate random initialization vectors for each encryption operation rather than reusing portions of the secret key. The fix should implement proper random IV generation that conforms to cryptographic best practices and follows the recommendations outlined in NIST SP 800-38A for counter mode encryption. Additionally, security teams should conduct comprehensive audits of all cryptographic implementations within their infrastructure to identify similar patterns that may have been overlooked, ensuring that no other systems are vulnerable to the same predictable IV usage patterns that characterize this specific vulnerability.