CVE-2019-17007 in Network Security Services
Summary
by MITRE • 10/23/2020
In Network Security Services before 3.44, a malformed Netscape Certificate Sequence can cause NSS to crash, resulting in a denial of service.
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Analysis
by VulDB Data Team • 11/26/2020
The vulnerability identified as CVE-2019-17007 resides within the Network Security Services (NSS) cryptographic library, which serves as a foundational component for security protocols across various applications including web browsers, email clients, and enterprise security solutions. This flaw manifests when NSS encounters a malformed Netscape Certificate Sequence during certificate processing operations, specifically within the certificate parsing and validation mechanisms that are critical for establishing secure communications. The issue affects NSS versions prior to 3.44, representing a significant security gap that could be exploited by adversaries to disrupt service availability.
The technical root cause of this vulnerability stems from inadequate input validation within NSS's certificate handling routines. When processing certificate data, NSS fails to properly validate the structure and content of Netscape Certificate Sequences, which are specific formats used in certain certificate extensions. This parsing failure occurs during the certificate validation phase where the library attempts to interpret certificate data structures. The malformed sequence triggers an unhandled exception or memory access violation that causes the NSS library to terminate abruptly, leading to application crashes and subsequent denial of service conditions. This represents a classic buffer over-read or parsing error that falls under the category of improper input validation as defined by CWE-20.
The operational impact of CVE-2019-17007 extends beyond simple application crashes to encompass broader service availability concerns across systems that depend on NSS for secure communications. When exploited, this vulnerability can cause cascading failures in web servers, email gateways, and other network infrastructure components that rely on NSS for SSL/TLS certificate processing. The vulnerability is particularly concerning because it can be triggered through legitimate certificate processing operations, making it difficult to distinguish between malicious exploitation and legitimate certificate handling. Attackers could potentially craft malicious certificates or manipulate certificate chains to trigger this condition, thereby causing denial of service against targeted systems. This aligns with ATT&CK technique T1499.004 which involves network denial of service attacks through exploitation of software vulnerabilities.
Organizations utilizing NSS-based systems should prioritize immediate remediation through patching to version 3.44 or later, which contains the necessary validation fixes to prevent malformed certificate sequences from causing crashes. Additionally, implementing certificate validation monitoring and alerting systems can help detect potential exploitation attempts. Network segmentation and certificate validation controls should be strengthened to limit the impact of potential exploitation. The vulnerability demonstrates the critical importance of robust input validation in cryptographic libraries, as even malformed input should not result in application termination. Security teams should also consider implementing certificate pre-validation processes and maintaining comprehensive logging of certificate processing activities to detect anomalous behavior that might indicate exploitation attempts. This vulnerability serves as a reminder of the essential need for thorough testing and validation of cryptographic libraries against malformed inputs to prevent denial of service conditions that can severely impact operational availability.