CVE-2007-0008 in Mozilla
Summary
by MITRE
Integer underflow in the SSLv2 support in Mozilla Network Security Services (NSS) before 3.11.5, as used by Firefox before 1.5.0.10 and 2.x before 2.0.0.2, SeaMonkey before 1.0.8, Thunderbird before 1.5.0.10, and certain Sun Java System server products before 20070611, allows remote attackers to execute arbitrary code via a crafted SSLv2 server message containing a public key that is too short to encrypt the "Master Secret", which results in a heap-based overflow.
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Analysis
by VulDB Data Team • 01/12/2025
The vulnerability described in CVE-2007-0008 represents a critical integer underflow flaw within the SSLv2 implementation of Mozilla Network Security Services NSS library. This vulnerability affects a wide range of applications including Firefox versions prior to 1.5.0.10 and 2.x versions prior to 2.0.0.2, SeaMonkey before 1.0.8, Thunderbird before 1.5.0.10, and various Sun Java System server products released before June 11, 2007. The flaw specifically manifests in the handling of SSLv2 server messages where the system fails to properly validate the length of public keys used for encrypting the Master Secret during the SSL handshake process.
The technical execution of this vulnerability relies on the manipulation of integer values within the NSS library's SSLv2 processing code. When a malicious server presents an SSLv2 message containing a public key that is insufficiently long to properly encrypt the Master Secret, the system experiences an integer underflow condition. This occurs because the code does not properly check that the key length meets minimum requirements before proceeding with encryption operations. The underflow results in incorrect memory calculations that ultimately lead to a heap-based buffer overflow, providing attackers with the opportunity to execute arbitrary code on the target system.
The operational impact of this vulnerability extends across multiple client and server applications that utilize the affected NSS library version. Attackers can exploit this weakness by establishing a malicious SSLv2 connection to a vulnerable system, causing the heap overflow condition that may result in remote code execution with the privileges of the affected application. This type of vulnerability falls under CWE-191, Integer Underflow, and can be mapped to ATT&CK technique T1203, Exploitation for Client Execution, when targeting web browsers and email clients. The vulnerability's exploitation vector is particularly dangerous because it can be triggered through normal SSL handshake operations without requiring any special privileges from the attacker.
Mitigation strategies for this vulnerability require immediate patching of all affected applications and systems. Organizations should upgrade to NSS versions 3.11.5 or later, along with corresponding updates to Firefox, SeaMonkey, Thunderbird, and Sun Java System server products. Additionally, administrators should consider disabling SSLv2 support entirely in their configurations, as this protocol version contains numerous security weaknesses beyond this specific vulnerability. The implementation of network monitoring and intrusion detection systems can help identify attempts to exploit this vulnerability by monitoring for unusual SSL handshake patterns and malformed SSLv2 messages. Security teams should also implement proper application whitelisting and privilege separation to limit the potential impact if exploitation occurs, as the heap overflow could allow attackers to gain full system control when successful.