Source: PSIRT-CNA@flexerasoftware.com
register.php in The Address Book 1.04e allows remote attackers to bypass the "Allow User Self-Registration" setting and create arbitrary users by setting the mode parameter to "confirm".
CVE-2006-4580 exposes a critical vulnerability in The Address Book 1.04e, allowing remote attackers to bypass user registration restrictions and create unauthorized user accounts. This can lead to unauthorized access, data breaches, and potential system compromise due to the creation of malicious user accounts.
Step 1: Target Identification: Identify a vulnerable instance of The Address Book 1.04e.
Step 2: Payload Construction: Craft a malicious HTTP request targeting register.php. The request will include the mode=confirm parameter.
Step 3: Request Submission: Send the crafted HTTP request to the vulnerable server.
Step 4: User Creation: The server, due to the vulnerability, processes the request and creates a new user account, bypassing the self-registration restrictions.
Step 5: Account Access: The attacker can then use the newly created credentials to log in and access the application.
The vulnerability stems from a flawed implementation in register.php. The script fails to properly validate the mode parameter. Specifically, the code does not adequately check if self-registration is enabled before processing a registration request with mode=confirm. This allows attackers to directly trigger the user creation process, bypassing the intended security measure. The root cause is a missing or inadequate check on the configuration setting related to self-registration, leading to an authentication bypass vulnerability. The flawed logic allows an attacker to manipulate the mode parameter to force user creation, regardless of the administrator's intended configuration.
Due to the age of the vulnerability, it's unlikely to be directly associated with specific APT groups. However, it could be leveraged by various threat actors for initial access or privilege escalation. This vulnerability is not listed on the CISA KEV.
Monitor web server logs (e.g., Apache, Nginx) for suspicious POST requests to register.php with the mode=confirm parameter.
Analyze HTTP request logs for unusual user agent strings or patterns associated with automated exploitation tools.
Implement file integrity monitoring to detect unauthorized modifications to register.php or other related files.
Monitor for the creation of new user accounts, especially those with unusual usernames or privileges.
Upgrade to a patched version of The Address Book (if available).
If upgrading is not possible, disable user self-registration in the application's configuration.
Implement input validation on the mode parameter in register.php to ensure it only accepts allowed values (e.g., values related to legitimate registration flows).
Review and harden the web server configuration to prevent unauthorized access to the application's files.
Implement a Web Application Firewall (WAF) to filter malicious requests.
Regularly scan the system for known vulnerabilities using vulnerability scanners.