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diff --git a/docs/binaryonly_fuzzing.txt b/docs/binaryonly_fuzzing.txt new file mode 100644 index 00000000..ed654e2a --- /dev/null +++ b/docs/binaryonly_fuzzing.txt @@ -0,0 +1,115 @@ + +Fuzzing binary-only programs with afl++ +======================================= + +afl++, libfuzzer and others are great if you have the source code, and +it allows for very fast and coverage guided fuzzing. + +However, if there is only the binary program and not source code available, +then standard afl++ (dumb mode) is not effective. + +The following is a description of how these can be fuzzed with afl++ + +!!!!! +DTLR: try DYNINST with afl-dyninst. If it produces too many crashes then + use afl -Q qemu_mode. +!!!!! + + +QEMU +---- +Qemu is the "native" solution to the program. +It is available in the ./qemu_mode/ directory and once compiled it can +be accessed by the afl-fuzz -Q command line option. +The speed decrease is at about 50% +It the easiest to use alternative and even works for cross-platform binaries. + +As it is included in afl++ this needs no URL. + + +DYNINST +------- +Dyninst is a binary instrumentation framework similar to Pintool and Dynamorio +(see far below). Howver whereas Pintool and Dynamorio work at runtime, dyninst +instruments the target at load time, and then let it run. +This is great for some things, e.g. fuzzing, and not so effective for others, +e.g. malware analysis. + +So what we can do with dyninst is taking every basic block, and put afl's +instrumention code in there - and then save the binary. +Afterwards we can just fuzz the newly saved target binary with afl-fuzz. +Sounds great? It is. The issue though - this is a non-trivial problem to +insert instructions, which changes addresses in the process space and that +everything still works afterwards. Hence more often than not binaries +crash when they are run. + +The speed decrease is about 25-35% + +So if dyninst works, its the best option available. Otherwise it just doesn't +work well. + +https://github.com/vanhauser-thc/afl-dyninst + + +INTEL-PT +-------- +The big issue with Intel's PT is the small buffer size and the complex +encoding of the debug information collected through PT. +This makes the decoding very CPU intensive, hence slow and using up twice +the CPU resources. So to fairly compare Intel PT based afl fuzzers with +native afl or afl qemu we need to calculate in the higher CPU resources used. +As a result, the overall speed decrease is about 85-90% + +there are two afl intel-pt implementations: + +1. https://github.com/junxzm1990/afl-pt + => this needs Ubuntu 14.04.05 without any updates and the 4.4 kernel. + +2. https://github.com/hunter-ht-2018/ptfuzzer + => this needs a 4.14 or 4.15 kernel. the "nopti" kernel boot option must + be used + + +CORESIGHT +--------- + +Coresight is the ARM answer to Intel's PT. +There is no implementation so far which handle coresight and getting +it working on an ARM Linux is very difficult due custom kernel building +on embedded systems is difficult. And finding one that has coresight in +the ARM chip is difficult too. +My guess is that it is slower than Qemu, but faster than Intel PT. +If anyone finds any coresight implemention for afl please ping me: +vh@thc.org + + +PIN & DYNAMORIO +--------------- + +Pintool and Dynamorio are dynamic instrumentation engines, and they can be +used for getting basic block information at runtime. +Pintool is only available for Intel x32/x64 on Linux, Mac OS and Windows +whereas Dynamorio is additionally available for ARM and AARCH64. +Dynamorio is also 10x faster than Pintool. + +The big issue with Dynamorio (and therefore Pintool too) is speed. +Dynamorio has a speed decrease of 98-99% +Pintool has a speed decrease of 99.5% + +Hence Dynamorio is the option to go for if everything fails, and Pintool +only if Dynamorio fails too. + +Dynamorio solutions: + https://github.com/vanhauser-thc/afl-dynamorio + https://github.com/mxmssh/drAFL + https://github.com/googleprojectzero/winafl/ <= very good but windows only + +Pintool solutions: + https://github.com/vanhauser-thc/afl-pin + https://github.com/mothran/aflpin + https://github.com/spinpx/afl_pin_mode <= only old Pintool version supported + + +That's it! +News, corrections, updates? +Email vh@thc.org |