H3-2025-0041

SSH Known Hosts File Exposure

Description

The SSH Known Hosts file is normally used to store fingerprints of remote SSH servers to help prevent man-in-the-middle attacks. However, when the .ssh/known_hosts file is inadvertently exposed by being placed in a publicly accessible directory or served via a web server, it creates a misconfiguration vulnerability that can provide attackers with valuable information about the network's internal infrastructure. Although the file typically contains public host key fingerprints rather than private keys, the disclosure may allow malicious actors to deduce the types of cryptographic algorithms used, SSH configurations in place, and potentially even infer the existence of other sensitive files or misconfigurations within the system. In some instances, attackers may leverage this information as part of a larger reconnaissance effort, mapping out a network's topology and identifying potential targets for further exploitation. The risk is amplified if other system directories are similarly exposed, or if the known_hosts file is used in combination with other misconfigured services. While the immediate impact may seem low, it can contribute to a broader attack surface by providing a starting point for unauthorized access attempts and network attacks. Organizations should review their server configurations and enforce strict access controls to prevent unintended file disclosure and ensure proper file system segregation.

Impact

Exploitation of this vulnerability can lead to unauthorized disclosure of SSH configuration details, enabling attackers to perform network reconnaissance and plan further targeted attacks. The exposure of host fingerprints could also aid in crafting more sophisticated compromise strategies against related systems.

References

• SSH Known Hosts