Putty Exposure Scanner

Putty is a widely used free and open-source terminal emulator, serial console, and network file transfer application. It is mainly used by system administrators and developers to connect to remote systems securely. The software supports various network protocols, including SSH, Telnet, and Rlogin, making it versatile for use in different networking environments. Putty is available for various operating systems, including Windows, macOS, and Unix, which increases its adoption across different platforms. Users can manage and configure remote servers, making it an essential tool in IT infrastructure management. Its capability to handle key files securely is crucial for maintaining encrypted connections and password-less logins.

The vulnerability detected by this scanner involves the exposure of Putty internal user key files. Such files are crucial for securing SSH connections and, if disclosed, can lead to unauthorized access to sensitive systems. This type of vulnerability is categorized as file disclosure, where sensitive file contents are unknowingly made accessible to external parties. The exposure often results from insecure file storage or improper handling of key files, placing emphasis on file location and naming conventions. The vulnerability poses significant risks to system security, potentially allowing attackers to impersonate legitimate users. Addressing this exposure is critical to maintaining a secure environment.

The technical details of this vulnerability revolve around exposing private key files used by Putty. The scanner targets common file paths like `{{BaseURL}}/my.ppk` and `{{BaseURL}}/putty.ppk`, where key files might be inadvertently stored. These key files are identified by specific content markers such as "PuTTY-User-Key-File" and "Encryption:". The matching process checks HTTP status codes to ensure the presence of these files. If detected, attackers could exploit key details to gain unauthorized access to associated systems. Ensuring that such files are adequately secured and not publicly accessible is vital.

If exploited, the file disclosure vulnerability can have severe implications, including unauthorized system access and potential data breaches. Attackers could leverage exposed key files to initiate unauthorized SSH sessions, bypassing authentication mechanisms. This can lead to the execution of malicious commands, data exfiltration, or system compromise. The organization's network could be at risk, affecting both internal operations and customer-facing services. Consequently, the damage could extend to brand reputation and financial losses, highlighting the need for immediate remediation measures.

REFERENCES

• https://github.com/detectify/ugly-duckling/blob/master/modules/crowdsourced/putty-private-key-disclosure.json