Authentication Bypass and Information Disclosure in Senior Rubiweb

CVE-2019-19550 is an authentication bypass vulnerability affecting Senior Rubiweb versions 6.2.34.28 and 6.2.34.37. The flaw exists in the application's connector component, which fails to properly enforce access controls on certain administrative actions. An unauthenticated remote attacker can leverage this by sending crafted HTTP requests to the /rubiweb/conector endpoint. Successful exploitation grants the attacker access to sensitive information and administrative functions that are intended to be restricted to authorized personnel. Given that functional exploit patterns have been published, organizations utilizing these versions of Rubiweb are at an increased risk of unauthorized data exposure and potential administrative compromise.

Attack Chain

1. Attacker performs reconnaissance to identify internet-facing instances of the Senior Rubiweb application by checking the standard /rubiweb/ portal.
2. Attacker confirms the version of the Rubiweb instance to determine if it is vulnerable to CVE-2019-19550.
3. Attacker crafts a malicious HTTP GET request targeting the /rubiweb/conector endpoint.
4. Attacker includes specific parameters such as ACAO=EXESENHA&SIS=FP&LOGINKIND=1 to bypass the application's authentication layer.
5. The vulnerable server processes the request without validating the session or credentials.
6. The server returns sensitive information or provides access to the targeted administrative function to the attacker.
7. Attacker extracts sensitive data from the unauthorized administrative responses.

Impact

Successful exploitation of CVE-2019-19550 results in unauthorized access to sensitive information stored within the Senior Rubiweb application. This impacts the confidentiality of the application data and allows an attacker to interact with administrative interfaces without valid credentials, potentially leading to further compromise of the affected environment.

Recommendation

• Patch Senior Rubiweb to the latest supported version to mitigate CVE-2019-19550.
• Deploy the Sigma rule below to detect attempts to access the vulnerable connector endpoint without valid authorization.
• Monitor web server logs for HTTP requests directed at /rubiweb/conector containing sensitive query parameters.
• Restrict access to the Rubiweb administrative interface to known, trusted IP addresses at the network perimeter.