CVE-2009-3983 in Firefox
Summary
by MITRE
Mozilla Firefox before 3.0.16 and 3.5.x before 3.5.6, and SeaMonkey before 2.0.1, allows remote attackers to send authenticated requests to arbitrary applications by replaying the NTLM credentials of a browser user.
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Analysis
by VulDB Data Team • 08/30/2021
This vulnerability exists in Mozilla Firefox versions prior to 3.0.16 and 3.5.x versions prior to 3.5.6, as well as in SeaMonkey versions before 2.0.1, representing a critical security flaw that enables remote attackers to exploit NTLM authentication mechanisms. The vulnerability stems from improper handling of NTLM authentication credentials within the browser's authentication framework, specifically allowing attackers to replay stored NTLM credentials to gain unauthorized access to applications that rely on NTLM authentication. This issue falls under the CWE-502 vulnerability category, which deals with deserialization of untrusted data, though in this case it manifests as improper authentication handling rather than direct deserialization. The flaw operates by leveraging the browser's NTLM authentication process to capture and reuse valid authentication tokens, effectively bypassing normal security boundaries and enabling unauthorized access to network resources that would normally require proper authentication.
The technical implementation of this vulnerability involves the browser's handling of NTLM authentication challenges and responses within the HTTP authentication framework. When a user accesses a web application that requires NTLM authentication, the browser stores the authentication credentials in memory or cache. Attackers can exploit this by crafting malicious web content that triggers NTLM authentication requests, then intercepting and replaying the authentication tokens to access other applications or resources that trust the user's credentials. This exploitation technique aligns with ATT&CK tactics involving credential access and privilege escalation, specifically targeting the T1075 credential access technique. The vulnerability particularly affects environments where NTLM authentication is used, such as corporate networks with Windows Active Directory integration, making it especially dangerous in enterprise environments where authentication boundaries are critical.
The operational impact of this vulnerability extends beyond simple unauthorized access to encompass potential lateral movement within networks and escalation of privileges. Attackers can leverage this flaw to access internal network resources, file servers, and other applications that rely on NTLM authentication without requiring additional credentials or bypassing network security controls. The vulnerability is particularly concerning because it operates at the browser level, making it difficult to detect and prevent through traditional network monitoring approaches. Organizations using affected browser versions face significant risk of data breaches, unauthorized system access, and potential compromise of sensitive corporate resources. The flaw also impacts the integrity of authentication systems by allowing attackers to replay valid credentials, potentially leading to unauthorized changes to system configurations or data manipulation. This vulnerability demonstrates the importance of proper authentication handling and credential management in web browsers, particularly in environments where multiple authentication protocols are in use.
Mitigation strategies for this vulnerability require immediate patching of affected browser versions to the latest secure releases, as well as implementing network-level controls to limit NTLM authentication exposure. Organizations should disable NTLM authentication where possible and implement stronger authentication mechanisms such as Kerberos or modern authentication protocols. Network segmentation and firewall rules should be configured to restrict access to internal resources from untrusted networks. Browser security policies should be enforced to disable automatic authentication and credential caching for sensitive applications. Additionally, security monitoring should be enhanced to detect unusual authentication patterns and credential replay attempts, which can serve as indicators of exploitation attempts. The vulnerability highlights the need for comprehensive authentication security practices and the importance of keeping browser software updated to address known security flaws. Organizations should also consider implementing multi-factor authentication and privileged access management solutions to reduce the impact of credential-based attacks.