CVE-2006-7175 in Sendmail
Summary
by MITRE
The version of Sendmail 8.13.1-2 on Red Hat Enterprise Linux 4 Update 4 and earlier does not allow the administrator to disable SSLv2 encryption, which could cause less secure channels to be used than desired.
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Analysis
by VulDB Data Team • 07/03/2017
The vulnerability identified as CVE-2006-7175 affects Sendmail version 8.13.1-2 running on Red Hat Enterprise Linux 4 Update 4 and earlier systems. This issue represents a significant security weakness in the cryptographic configuration of the mail transfer agent that could potentially expose organizations to man-in-the-middle attacks and eavesdropping. The problem stems from the inability of system administrators to explicitly disable SSLv2 encryption protocols, forcing the system to rely on less secure cryptographic methods that may be vulnerable to various attack vectors.
Sendmail, as a widely deployed mail transfer agent, serves as a critical component in enterprise email infrastructure and is responsible for handling sensitive communications between organizations. The specific flaw lies in the software's default configuration where SSLv2 protocol support cannot be disabled through administrative controls, even when administrators explicitly wish to enforce stronger cryptographic standards. This limitation creates a scenario where the system may negotiate and accept weaker SSLv2 connections when newer, more secure protocols are available, undermining the overall security posture of the email infrastructure.
The operational impact of this vulnerability extends beyond simple cryptographic weakness to encompass broader security implications for email communications. Organizations using affected Sendmail versions may unknowingly permit connections that utilize the deprecated SSLv2 protocol, which is known to have multiple security weaknesses including weak encryption algorithms and known vulnerabilities such as the POODLE attack. This could allow adversaries to intercept and potentially modify email communications, particularly when clients or servers do not properly enforce secure protocol versions. The vulnerability directly relates to CWE-310, which addresses cryptographic weaknesses in software implementations.
From an attack perspective, this vulnerability aligns with techniques described in the MITRE ATT&CK framework under the T1566 tactic for "Phishing" and T1046 for "Network Service Scanning" where attackers might exploit weak encryption to gain unauthorized access to email communications. The lack of administrative control over SSL protocol selection creates a persistent security gap that could be exploited by threat actors who specifically target older cryptographic protocols. Security professionals should note that SSLv2 has been deprecated for years due to its inherent security flaws and should never be used in production environments, yet this vulnerability prevents administrators from enforcing such best practices.
The recommended mitigation strategy involves upgrading to a newer version of Sendmail that properly supports disabling SSLv2 protocols and implementing proper cryptographic configuration management. Administrators should ensure that their systems enforce the use of TLS 1.2 or higher protocols and disable support for older, vulnerable cryptographic standards. Additionally, organizations should conduct comprehensive vulnerability assessments to identify all instances of affected Sendmail versions and implement proper monitoring to detect any attempts to establish SSLv2 connections. The vulnerability demonstrates the critical importance of maintaining up-to-date cryptographic software and the necessity of proper administrative controls over security configuration parameters.