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50 lines
2.0 KiB
50 lines
2.0 KiB
2 months ago
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=====================
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AFL quick start guide
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=====================
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You should read docs/README. It's pretty short. If you really can't, here's
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how to hit the ground running:
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1) Compile AFL with 'make'. If build fails, see docs/INSTALL for tips.
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2) Find or write a reasonably fast and simple program that takes data from
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a file or stdin, processes it in a test-worthy way, then exits cleanly.
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If testing a network service, modify it to run in the foreground and read
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from stdin. When fuzzing a format that uses checksums, comment out the
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checksum verification code, too.
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The program must crash properly when a fault is encountered. Watch out for
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custom SIGSEGV or SIGABRT handlers and background processes. For tips on
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detecting non-crashing flaws, see section 11 in docs/README.
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3) Compile the program / library to be fuzzed using afl-gcc. A common way to
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do this would be:
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CC=/path/to/afl-gcc CXX=/path/to/afl-g++ ./configure --disable-shared
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make clean all
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If program build fails, ping <afl-users@googlegroups.com>.
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4) Get a small but valid input file that makes sense to the program. When
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fuzzing verbose syntax (SQL, HTTP, etc), create a dictionary as described in
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dictionaries/README.dictionaries, too.
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5) If the program reads from stdin, run 'afl-fuzz' like so:
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./afl-fuzz -i testcase_dir -o findings_dir -- \
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/path/to/tested/program [...program's cmdline...]
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If the program takes input from a file, you can put @@ in the program's
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command line; AFL will put an auto-generated file name in there for you.
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6) Investigate anything shown in red in the fuzzer UI by promptly consulting
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docs/status_screen.txt.
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That's it. Sit back, relax, and - time permitting - try to skim through the
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following files:
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- docs/README - A general introduction to AFL,
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- docs/perf_tips.txt - Simple tips on how to fuzz more quickly,
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- docs/status_screen.txt - An explanation of the tidbits shown in the UI,
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- docs/parallel_fuzzing.txt - Advice on running AFL on multiple cores.
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