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Configuration Fuzzing for Software Vulnerability Detection. Huning Dai, Chris Murphy, Gail Kaiser Columbia University. Observation. Most vulnerabilities only reveal themselves under certain conditions: A. particular inputs Fuzz Testing (Miller et al., 1988 )
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Configuration Fuzzing for Software Vulnerability Detection Huning Dai, Chris Murphy, Gail Kaiser Columbia University
Observation Most vulnerabilities only reveal themselves under certain conditions: A. particular inputs Fuzz Testing (Miller et al., 1988 ) B. particular configurations of the software Configuration Testing (Memon and Porter et al., 2004) C. particular runtime environment. Fault Injection (Hsueh et al., 1997)
Our Solution • Configuration Fuzzing A. Instead of generating random inputs, Configuration Fuzzing mutates the application configuration using a covering array algorithm. B. To increase effectiveness, Configuration Fuzzing tests are carried out “In Vivo” after a software is released, with real-world inputs and runtime environment. C. Instead of only checking for failure, surveillance functions are run throughout the tests; these functions check for violations of “security invariants” and log detailed information.
Overview • Background • Model • ConFu Framework • Case Studies • Limitations and Conclusion
Background • In Vivo Testing (Murphy et al., 2009) Executes tests in the context of the running program after the software is released without affecting the main process. • Security Invariants (Biskup, 2009) Not merely const int security; const char secure; But rules…
Introduction to ConFu • ConFu: CONfiguration FUzzing testing framework • Steps: 1. Identifying the configuration variables 2. Generating fuzzing code 3. Identifying functions to test 4. Generating test code 5. Executing tests
STEP 1 • Identifying the configuration variables Part of the annotated configuration file of OpenSSH
STEP 2 • Generating fuzzing code An example fuzzer for OpenSSH
STEP 3 & STEP 4 • Identifying functions to test do_child() _do_child() • Generating test code Test function for do_child()
STEP 5 • Executing tests do_child(Wrapper) fork() test_do_child(test) _do_child(original) exit continue Wrapper function for do_child()
Case Studies: Feasibility • Reproduce known vulnerabilities and use ConFu to detect them. CVE-2000-0525: early versions of OpenSSH do not properly drop privileges when the UseLogin option is enabled, which allow local users to execute arbitrary commands by providing the command to the ssh daemon. CVE-2009-2958: The tftp_request function in tftp.c in dnsmasq before 2.50, when --enable-tftp is used, allows remote attackers to cause a denial of service (NULL pointer dereference and daemon crash) via a TFTP read (aka RRQ) request.
Case Studies: Performance • Target program: OpenSSH 2.1.0 • Chosen function: do_child() • Configuration: permit root login, ignore rhosts, ignore user known hosts, strict modes, x11 forwarding … a total of 15 configuration variables. • Environment: Intel Core2Quad Q6600 server with 2.40GHz and 2GB of RAM running Ubuntu 8.04.3
Case Studies: Performance • Results Overhead of instrumented do_child()(in seconds) with varying number of tests
Limitations and Future Work • Testers’ intervention is required to identify the functions to test • A priori knowledge of the potential exploitation behavior is required
Conclusion • Our contribution is an approach that checks for software vulnerability after the software is released and developed a testing framework based on this approach. • Useful in helping developers build more secure software and improve the security of existing software systems.
Configuration Fuzzing for Software Vulnerability Detection Huning Dai dai@cs.columbia.edu