Vulnerabilities > CVE-2023-28857 - Insufficiently Protected Credentials vulnerability in Apereo Central Authentication Service
Summary
Apereo CAS is an open source multilingual single sign-on solution for the web. Apereo CAS can be configured to use authentication based on client X509 certificates. These certificates can be provided via TLS handshake or a special HTTP header, such as “ssl_client_cert”. When checking the validity of the provided client certificate, X509CredentialsAuthenticationHandler performs check that this certificate is not revoked. To do so, it fetches URLs provided in the “CRL Distribution Points” extension of the certificate, which are taken from the certificate itself and therefore can be controlled by a malicious user. If the CAS server is configured to use an LDAP server for x509 authentication with a password, for example by setting a “cas.authn.x509.ldap.ldap-url” and “cas.authn.x509.ldap.bind-credential” properties, X509CredentialsAuthenticationHandler fetches revocation URLs from the certificate, which can be LDAP urls. When making requests to this LDAP urls, Apereo CAS uses the same password as for initially configured LDAP server, which can lead to a password leak. An unauthenticated user can leak the password used to LDAP connection configured on server. This issue has been addressed in version 6.6.6. Users are advised to upgrade. There are no known workarounds for this vulnerability.
Vulnerable Configurations
Common Weakness Enumeration (CWE)
Common Attack Pattern Enumeration and Classification (CAPEC)
- Session Sidejacking Session sidejacking takes advantage of an unencrypted communication channel between a victim and target system. The attacker sniffs traffic on a network looking for session tokens in unencrypted traffic. Once a session token is captured, the attacker performs malicious actions by using the stolen token with the targeted application to impersonate the victim. This attack is a specific method of session hijacking, which is exploiting a valid session token to gain unauthorized access to a target system or information. Other methods to perform a session hijacking are session fixation, cross-site scripting, or compromising a user or server machine and stealing the session token.
- Lifting credential(s)/key material embedded in client distributions (thick or thin) An attacker examines a target application's code or configuration files to find credential or key material that has been embedded within the application or its files. Many services require authentication with their users for the various purposes including billing, access control or attribution. Some client applications store the user's authentication credentials or keys to accelerate the login process. Some clients may have built-in keys or credentials (in which case the server is authenticating with the client, rather than the user). If the attacker is able to locate where this information is stored, they may be able to retrieve these credentials. The attacker could then use these stolen credentials to impersonate the user or client, respectively, in interactions with the service or use stolen keys to eavesdrop on nominally secure communications between the client and server.
- Password Recovery Exploitation An attacker may take advantage of the application feature to help users recover their forgotten passwords in order to gain access into the system with the same privileges as the original user. Generally password recovery schemes tend to be weak and insecure. Most of them use only one security question . For instance, mother's maiden name tends to be a fairly popular one. Unfortunately in many cases this information is not very hard to find, especially if the attacker knows the legitimate user. These generic security questions are also re-used across many applications, thus making them even more insecure. An attacker could for instance overhear a coworker talking to a bank representative at the work place and supplying their mother's maiden name for verification purposes. An attacker can then try to log in into one of the victim's accounts, click on "forgot password" and there is a good chance that the security question there will be to provide mother's maiden name. A weak password recovery scheme totally undermines the effectiveness of a strong password scheme.