CVE-2006-6071 in TWiki
Summary
by MITRE
TWiki 4.0.5 and earlier, when running under Apache 1.3 using ApacheLogin with sessions and "ErrorDocument 401" redirects to a valid wiki topic, does not properly handle failed login attempts, which allows remote attackers to read arbitrary content by cancelling out of a failed authentication with a valid username and invalid password.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 08/09/2018
The vulnerability described in CVE-2006-6071 represents a critical authentication bypass flaw in TWiki version 4.0.5 and earlier when deployed in specific Apache 1.3 configurations. This issue arises from improper handling of failed login attempts within the ApacheLogin authentication module, creating a scenario where attackers can exploit the session management and error redirection mechanisms to gain unauthorized access to protected content. The vulnerability specifically manifests when Apache 1.3 is configured with ApacheLogin authentication, sessions enabled, and ErrorDocument 401 directive redirecting to a valid wiki topic.
The technical flaw stems from the improper state management during authentication failures within the TWiki application's interaction with Apache's authentication framework. When a user attempts to authenticate with a valid username but invalid password, the system fails to properly terminate the authentication context or reset session state. This allows an attacker to cancel the authentication dialog and subsequently access content that should be restricted to authenticated users. The vulnerability is particularly dangerous because it leverages the legitimate error redirection mechanism that is typically used to guide users back to a valid login page or topic.
The operational impact of this vulnerability is severe as it enables remote attackers to bypass authentication mechanisms entirely without requiring valid credentials. An attacker can exploit this flaw by first identifying a valid username through enumeration techniques, then attempting authentication with that username and a random password. When the authentication fails and the user cancels the dialog, the system incorrectly maintains access to previously restricted content. This creates a persistent backdoor that allows unauthorized access to sensitive wiki content, user data, and potentially administrative functions depending on the wiki's configuration and permissions structure.
This vulnerability aligns with CWE-287 which addresses improper authentication issues in software systems. The flaw demonstrates a classic case of insufficient session management and authentication state handling, where the application fails to properly validate or invalidate authentication contexts after failed attempts. From an attacker perspective, this vulnerability maps to ATT&CK technique T1078 which covers valid accounts and T1566 which covers credential harvesting through various means including authentication bypass methods. The attack chain typically involves user enumeration followed by authentication bypass, making it particularly dangerous in environments where user accounts are easily discoverable.
Mitigation strategies for this vulnerability include upgrading to TWiki version 4.0.6 or later where the authentication handling has been corrected, implementing proper session management controls, and configuring Apache to use more secure error redirection mechanisms that do not inadvertently grant access to protected content. Organizations should also consider implementing additional authentication layers such as two-factor authentication, restricting access to sensitive wiki content through network segmentation, and monitoring for unusual authentication patterns that might indicate exploitation attempts. The fundamental fix involves ensuring that failed authentication attempts properly terminate the user session and prevent subsequent access to restricted resources.