CVE-2014-1569 in Fusion Middleware
Summary
by MITRE
The definite_length_decoder function in lib/util/quickder.c in Mozilla Network Security Services (NSS) before 3.16.2.4 and 3.17.x before 3.17.3 does not ensure that the DER encoding of an ASN.1 length is properly formed, which allows remote attackers to conduct data-smuggling attacks by using a long byte sequence for an encoding, as demonstrated by the SEC_QuickDERDecodeItem function's improper handling of an arbitrary-length encoding of 0x00.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 06/22/2022
The vulnerability identified as CVE-2014-1569 resides within Mozilla Network Security Services (NSS) cryptographic library, specifically in the definite_length_decoder function located in lib/util/quickder.c. This flaw represents a critical issue in ASN.1 DER (Distinguished Encoding Rules) parsing that affects NSS versions prior to 3.16.2.4 and 3.17.x versions before 3.17.3. The vulnerability stems from insufficient validation of DER encoding length fields, creating a pathway for malicious actors to exploit improper handling of ASN.1 data structures through carefully crafted inputs that manipulate the encoding format.
The technical flaw manifests when the definite_length_decoder function fails to properly verify that DER encoding length fields are correctly formed according to ASN.1 standards. In standard DER encoding, length fields must follow specific rules where short form lengths are represented by a single byte with the most significant bit set to zero, while long form lengths use multiple bytes with the most significant bit set to one. The vulnerability occurs because NSS does not adequately validate these length fields, allowing attackers to craft inputs where the length field contains an arbitrary number of bytes that can be interpreted as a very large value, even when the actual data content is minimal.
This weakness enables remote attackers to conduct data-smuggling attacks by manipulating the DER encoding structure to include extended byte sequences that appear valid but contain malicious or unexpected data. The SEC_QuickDERDecodeItem function demonstrates this improper handling when processing arbitrary-length encodings of the value 0x00, which can be used to bypass normal parsing constraints. The impact extends beyond simple parsing errors as it allows attackers to inject additional data or manipulate the parsing process in ways that could lead to information disclosure, denial of service, or potentially more severe consequences depending on how the parsed data is subsequently processed.
The operational impact of this vulnerability is significant for any system utilizing NSS for cryptographic operations, particularly those handling X.509 certificates, SSL/TLS connections, or other ASN.1 encoded data. Attackers could exploit this weakness to bypass certificate validation, manipulate certificate data, or inject malicious content into otherwise legitimate cryptographic operations. The vulnerability aligns with CWE-129, which addresses improper validation of length fields, and relates to ATT&CK technique T1059.007 for execution through encoded command and control communications. Systems relying on NSS for secure communications, including web browsers, email clients, and network security appliances, would be particularly vulnerable to this type of attack vector.
Organizations should immediately upgrade to NSS versions 3.16.2.4 or 3.17.3 and later to remediate this vulnerability. Additional mitigations include implementing proper input validation for all ASN.1 encoded data, monitoring for unusual DER encoding patterns, and ensuring that cryptographic libraries are regularly updated and patched. Network segmentation and intrusion detection systems should be configured to monitor for potential exploitation attempts, while security teams should conduct thorough vulnerability assessments to identify systems still running affected NSS versions. The vulnerability demonstrates the critical importance of proper ASN.1 parsing validation in cryptographic libraries and underscores the need for comprehensive testing of encoding handling routines against malformed inputs.