Source: cve@mitre.org
iisPROTECT 2.1 and 2.2 allows remote attackers to bypass authentication via an HTTP request containing URL-encoded characters.
IISPROTECT 2.1 and 2.2 are vulnerable to a critical authentication bypass. Attackers can leverage URL-encoded characters in HTTP requests to circumvent security measures, potentially gaining unauthorized access to protected resources and sensitive data. This vulnerability poses a significant risk of data breaches and system compromise.
Step 1: Target Identification: Identify a server running iisPROTECT 2.1 or 2.2.
Step 2: Crafting the Payload: Construct an HTTP request that includes URL-encoded characters designed to bypass the authentication mechanism. This often involves encoding characters in the username or password fields.
Step 3: Payload Delivery: Send the crafted HTTP request to the vulnerable iisPROTECT server.
Step 4: Server Processing: The iisPROTECT software receives the request and attempts to authenticate the user.
Step 5: Authentication Bypass: Due to the vulnerability, the URL-encoded characters are not properly decoded or validated, allowing the attacker to bypass the authentication checks.
Step 6: Unauthorized Access: The attacker gains access to protected resources without proper credentials.
The vulnerability stems from inadequate input validation and improper handling of URL-encoded characters by iisPROTECT. Specifically, the software fails to correctly decode and sanitize URL-encoded characters before processing authentication requests. This allows attackers to craft malicious requests containing specially crafted URL-encoded sequences that, when decoded by the server, bypass the intended authentication checks. The root cause is a flaw in the character decoding logic, where the software doesn't properly handle the conversion of encoded characters to their original form, leading to a mismatch between the expected and actual request parameters. This could be due to a missing or incomplete regular expression or a flawed character mapping function. The lack of proper input validation allows the attacker to manipulate the request and gain unauthorized access. The flaw is not a buffer overflow or a race condition, but rather a logic error in the authentication process.
Due to the age of the vulnerability, it's unlikely to be directly associated with specific APT groups. However, any attacker seeking to compromise web servers could utilize this vulnerability. The vulnerability is not listed on the CISA KEV.
Analyze web server logs for suspicious HTTP requests containing URL-encoded characters in authentication-related fields (e.g., username, password, or session tokens).
Monitor network traffic for unusual patterns of URL-encoded characters in HTTP requests, especially those targeting authentication endpoints.
Implement a Web Application Firewall (WAF) with rules to detect and block malicious requests containing URL-encoded characters designed to bypass authentication.
Examine the iisPROTECT configuration files for any unusual settings or modifications.
Upgrade to a patched version of iisPROTECT or a more secure web application firewall (WAF).
Implement robust input validation to properly decode and sanitize all URL-encoded characters in incoming HTTP requests.
Review and update the web server configuration to ensure that URL encoding is handled securely.
Implement multi-factor authentication (MFA) to add an extra layer of security.
Regularly scan the system for vulnerabilities and apply security patches promptly.
Consider replacing iisPROTECT with a more modern and secure authentication solution.