A team of researchers from Ruhr University Bochum has recently reported on a vulnerability in the Secure Shell protocol, commonly known as ssh. This vulnerability, named “Terrapin,” allows hackers to manipulate data during the initial connection, potentially compromising certain security features. However, the impact of this attack is relatively minor, and the ability to exploit it is limited.
Terrapin leverages a man-in-the-middle attack to intercept and modify data during the opening of a secure shell connection. By tampering with certain parameters, attackers can alter the secure shell connection, notably by manipulating the extension data. This manipulation can disable additional security features requested by the server, such as time-locked data transmission to prevent keystroke guessing. However, fundamental security mechanisms like data encryption and protection against tampering remain intact.
In addition to requiring a man-in-the-middle interception, affected servers must also utilize specific encryption processes, namely ChaCha20-Poly1305 or CBC combined with Encrypt-then-MAC, for the attack to be successful. As a precautionary measure, server administrators may consider limiting the available encryption methods to mitigate potential risks.
TLDR: Researchers have discovered a vulnerability in the Secure Shell protocol known as Terrapin, allowing attackers to manipulate data during the connection setup phase. While this poses a potential risk, the impact of the attack is limited, and certain server configurations are required for exploitation. Server administrators should consider restrictive encryption practices as a precautionary measure.
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