Recently, Qualys found an exploit in OpenSSH’s sshd server application that they named regreSSHion. This exploit lets attackers run arbitrary code by exploiting a race condition in a signal handler.
wolfSSH is not a port or fork of OpenSSH. It is written from scratch by wolfSSL Inc. While wolfSSHd is using the same alarm signal to time out users, our signal handler only sets a flag. OpenSSH’s handler, on the other hand, called unsafe functions.
How wolfSSH Avoids This Vulnerability
wolfSSH’s signal handling is designed to be safer due to:
- Minimalist Signal Handling: Our handler only sets a flag, reducing race condition risks.
- Async-Signal Safe Operations: We ensure all operations within the signal handler are safe.
- Independent Implementation: wolfSSH is a complete rewrite, avoiding inherited vulnerabilities.
Conclusion
The regreSSHion exploit in OpenSSH underscores the need for safe signal handling. wolfSSH’s simple and secure approach to signal handling avoids the vulnerabilities found in OpenSSH, making it a safer choice for SSH server applications.
If you have any questions or want to talk about wolfSSH, please feel free to send us an email at facts@wolfssl.com or sales@wolfssl.com, or call us at +1 425 245 8247.
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