Michael Rash, Security Researcher

Software Release - fwknop-2.0.3

fwknop-2.0.3 released The fwknop-2.0.3 release of fwknop is available for download. This is an important release that tightens up the code in several areas based on excellent research performed by Fernando Arnaboldi of IOActive. I wish to thank Fernando for this work, and also Erik Gomez of IOActive as well for making this research possible. Fernando's research turned up potential DoS and/or code execution vulnerabilities in the fwknopd server for malicious authenticated clients, insecure filesystem permissions handling, and more. All of these issues have been fixed in the 2.0.3 release.

Here is the complete fwknop-2.0.3 ChangeLog:

  • [server] Fernando Arnaboldi from IOActive found several DoS/code execution vulnerabilities for malicious fwknop clients that manage to get past the authentication stage (so a such a client must be in possession of a valid access.conf encryption key). These vulnerabilities manifested themselves in the handling of malformed access requests, and both the fwknopd server code along with libfko now perform stronger input validation of access request data. These vulnerabilities affect pre-2.0.3 fwknop releases.
  • [server] Fernando Arnaboldi from IOActive found a condition in which the server did not properly validate allow IP addresses from malicious authenticated clients. This has been fixed with stronger allow IP validation.
  • [client+server] Fernando Arnaboldi from IOActive found that strict filesystem permissions for various fwknop files are not verified. Added warnings whenever permissions are not strict enough, and ensured that files created by the fwknop client and server are only set to user read/write.
  • [client] Fernando Arnaboldi from IOActive found a local buffer overflow in --last processing with a maliciously constructed ~/ file. This has been fixed with proper validation of arguments.
  • [server] Fernando Arnaboldi from IOActive found several conditions in which the server did not properly throw out maliciously constructed variables in the access.conf file. This has been fixed along with new fuzzing tests in the test suite.
  • [test suite] Added a new fuzzing capability to ensure proper server-side input validation. Fuzzing data is constructed with modified fwknop client code that is designed to emulate malicious behavior.
  • Fixed RPM builds by including the $(DESTDIR) prefix for uninstall-local and install-exec-hook stages in
The fwknop-2.0.3 ChangeLog can also be found here via the fwknop gitweb interface.