General Bytes Crypto Application Server (CAS) beginning with version 20201208 prior to 20220531.38 (backport) and 20220725.22 (mainline) contains an authentication bypass in the admin web interface. An unauthenticated attacker could invoke the same URL used by the products default-installation / first-admin creation page and create a new administrative account remotely. By gaining admin privileges, the attacker can change the ATM configuration resulting in redirected funds. Public vendor advisories and multiple independent writeups describe the vulnerability as a call to the page used for initial/default installation / first administration user creation; General Bytes has not publicly published the exact endpoint/parameter name. The issue was actively exploited in the wild against cloud-hosted and standalone CAS deployments (scanning exposed CAS instances on ports 7777/443), and publicly acknowledged by the General Bytes in September 2022.
Weakness
The product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources.
Potential Mitigations
- Divide the software into anonymous, normal, privileged, and administrative areas. Identify which of these areas require a proven user identity, and use a centralized authentication capability.
- Identify all potential communication channels, or other means of interaction with the software, to ensure that all channels are appropriately protected, including those channels that are assumed to be accessible only by authorized parties. Developers sometimes perform authentication at the primary channel, but open up a secondary channel that is assumed to be private. For example, a login mechanism may be listening on one network port, but after successful authentication, it may open up a second port where it waits for the connection, but avoids authentication because it assumes that only the authenticated party will connect to the port.
- In general, if the software or protocol allows a single session or user state to persist across multiple connections or channels, authentication and appropriate credential management need to be used throughout.
- Where possible, avoid implementing custom, “grow-your-own” authentication routines and consider using authentication capabilities as provided by the surrounding framework, operating system, or environment. These capabilities may avoid common weaknesses that are unique to authentication; support automatic auditing and tracking; and make it easier to provide a clear separation between authentication tasks and authorization tasks.
- In environments such as the World Wide Web, the line between authentication and authorization is sometimes blurred. If custom authentication routines are required instead of those provided by the server, then these routines must be applied to every single page, since these pages could be requested directly.
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
- For example, consider using libraries with authentication capabilities such as OpenSSL or the ESAPI Authenticator [REF-45].
References