CVE-2013-1740 in Network Security Services
Summary
by MITRE
The ssl_Do1stHandshake function in sslsecur.c in libssl in Mozilla Network Security Services (NSS) before 3.15.4, when the TLS False Start feature is enabled, allows man-in-the-middle attackers to spoof SSL servers by using an arbitrary X.509 certificate during certain handshake traffic.
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Analysis
by VulDB Data Team • 02/03/2019
The vulnerability identified as CVE-2013-1740 represents a critical security flaw in the Mozilla Network Security Services library that affects the secure communication protocols used by numerous applications and systems. This issue specifically targets the ssl_Do1stHandshake function within the sslsecur.c file of NSS versions prior to 3.15.4, where the TLS False Start feature creates a window of opportunity for attackers to exploit the certificate validation process during the initial handshake phase of SSL/TLS connections.
The technical exploitation of this vulnerability occurs when the TLS False Start feature is enabled, which is designed to improve performance by allowing application data to be sent before the handshake is complete. However, this optimization creates a security gap where malicious actors can manipulate the handshake process to present arbitrary X.509 certificates that would normally be rejected during normal certificate validation procedures. The flaw essentially allows attackers to bypass certificate verification mechanisms during specific phases of the SSL handshake, enabling them to establish seemingly secure connections while actually communicating with compromised intermediaries.
This vulnerability directly impacts the fundamental security guarantees of SSL/TLS protocols, particularly the authentication and integrity properties that ensure clients are communicating with legitimate servers. The man-in-the-middle attack vector enabled by CVE-2013-1740 undermines the trust model that SSL/TLS relies upon, potentially allowing attackers to intercept, modify, or redirect encrypted communications without detection. The impact extends beyond individual applications to affect entire ecosystems that depend on NSS for secure communications, including web browsers, email clients, and server applications.
From a cybersecurity perspective, this vulnerability aligns with CWE-295 which addresses improper certificate validation and represents a significant weakness in the certificate chain validation process. The attack pattern follows typical MITM techniques documented in the MITRE ATT&CK framework under the T1046 category for network service scanning and T1566 for credential harvesting through man-in-the-middle attacks. Organizations using affected NSS versions face substantial risk of data breaches, privacy violations, and potential regulatory compliance issues.
The recommended mitigation strategy involves immediate upgrading to NSS version 3.15.4 or later, which includes patches that address the certificate validation timing issue during TLS False Start operations. Additionally, administrators should consider temporarily disabling the TLS False Start feature in affected systems while applying the security updates. Security teams should monitor network traffic for signs of exploitation attempts and implement network-based intrusion detection systems to identify potential man-in-the-middle activity. Regular security assessments and vulnerability scanning should be conducted to ensure all systems utilizing NSS components remain protected against similar vulnerabilities.