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