CVE-2015-4515 in Firefox
Summary
by MITRE
Mozilla Firefox before 42.0, when NTLM v1 is enabled for HTTP authentication, allows remote attackers to obtain sensitive hostname information by constructing a crafted web site that sends an NTLM request and reads the Workstation field of an NTLM type 3 message.
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Analysis
by VulDB Data Team • 06/26/2022
This vulnerability exists in Mozilla Firefox versions prior to 42.0 where NTLM v1 authentication is enabled for HTTP connections. The flaw occurs when a malicious website constructs a crafted web page that triggers an NTLM authentication request, specifically targeting the NTLM type 3 message response. When Firefox processes this authentication flow, it inadvertently exposes the hostname information contained within the Workstation field of the NTLM type 3 message. This represents a significant information disclosure vulnerability that can be exploited by remote attackers to gather sensitive system information.
The technical mechanism behind this vulnerability involves the NTLM authentication protocol's handling of type 3 messages, which contain authentication data including the workstation name. When Firefox processes NTLM authentication requests, it fails to properly sanitize or validate the information extracted from these messages, allowing attackers to access the hostname field that typically contains system identification data. This issue falls under the CWE-200 category of "Information Exposure" and specifically relates to CWE-201 which addresses "Information Exposure Through Sent Data". The vulnerability is particularly concerning because it leverages the legitimate NTLM authentication mechanism to extract information that should remain protected within the authentication process.
From an operational perspective, this vulnerability enables remote attackers to gather hostname information from systems that are configured to use NTLM v1 authentication with Firefox. The exposed hostname data can provide attackers with valuable reconnaissance information about network infrastructure, potentially aiding in further attacks such as credential harvesting, network mapping, or targeted attacks against specific systems. This vulnerability is particularly dangerous in enterprise environments where NTLM authentication is commonly used for internal network access, as it can reveal internal hostnames and network topology information that should remain confidential.
The attack scenario begins with an attacker creating a malicious website that triggers NTLM authentication through a crafted web page. When a user accesses this page while Firefox is configured to use NTLM v1 authentication, the browser automatically sends an NTLM request to the attacker-controlled server. The attacker then captures the NTLM type 3 message and extracts the Workstation field, which contains the hostname information. This attack is classified under the ATT&CK technique T1071.004 "Application Layer Protocol: DNS" in the context of information gathering, and represents a form of credential theft through information exposure. The vulnerability demonstrates the importance of proper input validation and output sanitization in authentication protocols.
Mitigation strategies for this vulnerability include upgrading to Firefox version 42.0 or later, which contains the necessary patches to prevent the exposure of hostname information during NTLM authentication. Organizations should also consider disabling NTLM v1 authentication entirely, as it is inherently insecure and vulnerable to various attacks including this information disclosure issue. Security administrators should implement network monitoring to detect unusual NTLM authentication patterns and consider configuring Firefox to use more secure authentication methods such as Kerberos or modern HTTP authentication mechanisms. Additionally, regular security assessments should verify that authentication protocols are properly configured and that sensitive information is not inadvertently exposed through authentication flows. The patch for this vulnerability specifically addresses the improper handling of NTLM type 3 messages and ensures that hostname information is properly sanitized before being processed by the browser's authentication subsystem.