This tool is designed to use Intel's Pin Tool to instrument reverse engineering binaries and count instructions.
This tool is designed to use instruction counting as an avenue for Side Channel Analysis. By counting the number of instruction exeuted in a given reverse engineering program we can guess (Sometimes) that the more instructions that are executed per input, the closer we are to the flag.
Included in this repo is a script for pulling down Intel's PIN and instructions for building it on Ubuntu 16.04.
#This script will pull PIN and install dependencies needed. ./installPin.sh
PinCTF is implemented as a python script wrapping PIN. It will execute a pin command then read from PIN's produced inscount.out file
[chris@Thor pinCTF]$ ./pinCTF.py -h usage: pinCTF.py [-h] [-f FILE] [-a] [-al] [-i] [-il] [-p PINLOCATION] [-l PINLIBRARYLOCATION] [-c COUNT] [-s SEED] [-r RANGE] [-sl SEEDLENGTH] [-st SEEDSTART] [-t] [-tc THREADCOUNT] optional arguments: -h, --help show this help message and exit -f FILE, --file FILE file to run pin against -a, --arg Trace instructions for passed in argument -al, --argLength Trace instructions for passed in argument length -i, --input Trace instructions for given input -il, --inputLength Trace instructions for input length -p PINLOCATION, --pinLocation PINLOCATION Location of pin's directory -l PINLIBRARYLOCATION, --pinLibraryLocation PINLIBRARYLOCATION Location of pin's instruction0.so libraries -c COUNT, --count COUNT MaxLength to for length based pin -s SEED, --seed SEED Initial seed for input or arg pin -r RANGE, --range RANGE range of characters to iterate pin over -sl SEEDLENGTH, --seedLength SEEDLENGTH Initial seed length for input or arg pin -st SEEDSTART, --seedStart SEEDSTART Initial seed index for pin -t, --threading Enables threading -tc THREADCOUNT, --threadCount THREADCOUNT Number of threads
To compare instruction counts to length use the -il or -al commands The -c command is used to specifyhow many A's to test
./pinCTF.py -f examples/wyvern_c85f1be480808a9da350faaa6104a19b -il -l obj-intel64/ -c 30 Num : Instr Count AAAAAAAAAAAAAAAAAAA 1 : 2119788 2 : 2119789 3 : 2119789 4 : 2119784 5 : 2119788 6 : 2119789 7 : 2119791 8 : 2119782 9 : 2119786 10 : 2119787 11 : 2119791 12 : 2119786 13 : 2119790 14 : 2119791 15 : 2119818 16 : 2119822 17 : 2119826 18 : 2119825 19 : 2119831 20 : 2119824 21 : 2119830 22 : 2119831 23 : 2119835 24 : 2119826 25 : 2119830 26 : 2119831 27 : 2119835 28 : 2132982 29 : 2119834 30 : 2119863 [+] Found Num 28 : Count 2132982
Now we know we that the flag is 28 characters long and we can start looking for a flag of 28 characters.
Once you've found a length that seems to work you can use pin to change each value testing for instruction changes The -sl flag can be used to determine the length of the initial seed, and the -r flag can be used to choose what range to iterate over
./pinCTF.py -f examples/wyvern_c85f1be480808a9da350faaa6104a19b -i -l obj-intel64/ -sl 28 -r abcdefghijklmnopqrstuvwxyz012345_-+LVMA -sk [+] iter 0 using d for dAAAAAAAAAAAAAAAAAAAAAAAAAAA [+] iter 1 using r for drAAAAAAAAAAAAAAAAAAAAAAAAAA [+] iter 2 using 4 for dr4AAAAAAAAAAAAAAAAAAAAAAAAA [+] iter 3 using g for dr4gAAAAAAAAAAAAAAAAAAAAAAAA [+] iter 4 using 0 for dr4g0AAAAAAAAAAAAAAAAAAAAAAA [+] iter 5 using n for dr4g0nAAAAAAAAAAAAAAAAAAAAAA [+] iter 6 using _ for dr4g0n_AAAAAAAAAAAAAAAAAAAAA [+] iter 7 using o for dr4g0n_oAAAAAAAAAAAAAAAAAAAA [+] iter 8 using r for dr4g0n_orAAAAAAAAAAAAAAAAAAA [+] iter 9 using _ for dr4g0n_or_AAAAAAAAAAAAAAAAAA [+] iter 10 using p for dr4g0n_or_pAAAAAAAAAAAAAAAAA [+] iter 11 using 4 for dr4g0n_or_p4AAAAAAAAAAAAAAAA [+] iter 12 using t for dr4g0n_or_p4tAAAAAAAAAAAAAAA [+] iter 13 using r for dr4g0n_or_p4trAAAAAAAAAAAAAA [+] iter 14 using i for dr4g0n_or_p4triAAAAAAAAAAAAA [+] iter 15 using c for dr4g0n_or_p4tricAAAAAAAAAAAA [+] iter 16 using 1 for dr4g0n_or_p4tric1AAAAAAAAAAA [+] iter 17 using a for dr4g0n_or_p4tric1aAAAAAAAAAA [+] iter 18 using n for dr4g0n_or_p4tric1anAAAAAAAAA [+] iter 19 using _ for dr4g0n_or_p4tric1an_AAAAAAAA [+] iter 20 using i for dr4g0n_or_p4tric1an_iAAAAAAA [+] iter 21 using t for dr4g0n_or_p4tric1an_itAAAAAA [+] iter 22 using 5 for dr4g0n_or_p4tric1an_it5AAAAA [+] iter 23 using _ for dr4g0n_or_p4tric1an_it5_AAAA [+] iter 24 using L for dr4g0n_or_p4tric1an_it5_LAAA [+] iter 25 using L for dr4g0n_or_p4tric1an_it5_LLAA [+] iter 26 using V for dr4g0n_or_p4tric1an_it5_LLVA [+] iter 27 using M for dr4g0n_or_p4tric1an_it5_LLVM [+] Found pattern dr4g0n_or_p4tric1an_it5_LLVM
Script tricks for PIN
This process is pretty slow and can be sped up with threading. The -t (--threading) flag will enable threading and -tc represents the thread count
time ./pinCTF.py -f $(pwd)/examples/crypt4 -a -sl 26 --threading -tc 4 [+] iter 0 using d for dAAAAAAAAAAAAAAAAAAAAAAAAA [+] iter 1 using y for dyAAAAAAAAAAAAAAAAAAAAAAAA [+] iter 2 using n for dynAAAAAAAAAAAAAAAAAAAAAAA [+] iter 3 using 4 for dyn4AAAAAAAAAAAAAAAAAAAAAA [+] iter 4 using m for dyn4mAAAAAAAAAAAAAAAAAAAAA [+] iter 5 using 1 for dyn4m1AAAAAAAAAAAAAAAAAAAA [+] iter 6 using c for dyn4m1cAAAAAAAAAAAAAAAAAAA [+] iter 7 using a for dyn4m1caAAAAAAAAAAAAAAAAAA [+] iter 8 using l for dyn4m1calAAAAAAAAAAAAAAAAA [+] iter 9 using l for dyn4m1callAAAAAAAAAAAAAAAA [+] iter 10 using y for dyn4m1callyAAAAAAAAAAAAAAA [+] iter 11 using _ for dyn4m1cally_AAAAAAAAAAAAAA [+] iter 12 using d for dyn4m1cally_dAAAAAAAAAAAAA [+] iter 13 using 3 for dyn4m1cally_d3AAAAAAAAAAAA [+] iter 14 using c for dyn4m1cally_d3cAAAAAAAAAAA [+] iter 15 using r for dyn4m1cally_d3crAAAAAAAAAA [+] iter 16 using y for dyn4m1cally_d3cryAAAAAAAAA [+] iter 17 using p for dyn4m1cally_d3crypAAAAAAAA [+] iter 18 using t for dyn4m1cally_d3cryptAAAAAAA [+] iter 19 using 3 for dyn4m1cally_d3crypt3AAAAAA [+] iter 20 using d for dyn4m1cally_d3crypt3dAAAAA [+] iter 21 using _ for dyn4m1cally_d3crypt3d_AAAA [+] iter 22 using c for dyn4m1cally_d3crypt3d_cAAA [+] iter 23 using 0 for dyn4m1cally_d3crypt3d_c0AA [+] iter 24 using d for dyn4m1cally_d3crypt3d_c0dA [~] Largest instruction count found to match several others or very close [~] Locating largest difference from average instead [+] iter 25 using 3 for dyn4m1cally_d3crypt3d_c0d3 [+] Found pattern dyn4m1cally_d3crypt3d_c0d3 real 3m26.511s user 10m53.012s sys 2m21.344s
Some ctf binaries will validate input backwards to throw off fuzzers. using the -rev flag PinCTF is able to alter the input backwards
./pinCTF.py -f $(pwd)/examples/ELF-NoSoftwareBreakpoints -i -sl 25 -rev -t -tc 4 -r abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890_-@ [~] Running in reverse direction [+] iter 24 using S for AAAAAAAAAAAAAAAAAAAAAAAAS [+] iter 23 using k for AAAAAAAAAAAAAAAAAAAAAAAkS [+] iter 22 using c for AAAAAAAAAAAAAAAAAAAAAAckS [+] iter 21 using 0 for AAAAAAAAAAAAAAAAAAAAA0ckS [+] iter 20 using r for AAAAAAAAAAAAAAAAAAAAr0ckS [+] iter 19 using _ for AAAAAAAAAAAAAAAAAAA_r0ckS [+] iter 18 using T for AAAAAAAAAAAAAAAAAAT_r0ckS [+] iter 17 using N for AAAAAAAAAAAAAAAAANT_r0ckS [+] iter 16 using i for AAAAAAAAAAAAAAAAiNT_r0ckS [+] iter 15 using o for AAAAAAAAAAAAAAAoiNT_r0ckS [+] iter 14 using P for AAAAAAAAAAAAAAPoiNT_r0ckS [+] iter 13 using k for AAAAAAAAAAAAAkPoiNT_r0ckS [+] iter 12 using a for AAAAAAAAAAAAakPoiNT_r0ckS [+] iter 11 using 3 for AAAAAAAAAAA3akPoiNT_r0ckS [+] iter 10 using r for AAAAAAAAAAr3akPoiNT_r0ckS [+] iter 9 using B for AAAAAAAAABr3akPoiNT_r0ckS [+] iter 8 using _ for AAAAAAAA_Br3akPoiNT_r0ckS [+] iter 7 using e for AAAAAAAe_Br3akPoiNT_r0ckS [+] iter 6 using r for AAAAAAre_Br3akPoiNT_r0ckS [+] iter 5 using @ for AAAAA@re_Br3akPoiNT_r0ckS [+] iter 4 using W for AAAAW@re_Br3akPoiNT_r0ckS [+] iter 3 using d for AAAdW@re_Br3akPoiNT_r0ckS [+] iter 2 using r for AArdW@re_Br3akPoiNT_r0ckS [+] iter 1 using a for AardW@re_Br3akPoiNT_r0ckS [~] Largest instruction count found to match several others or very close [~] Locating largest difference from average instead [+] iter 0 using H for HardW@re_Br3akPoiNT_r0ckS [+] Found pattern HardW@re_Br3akPoiNT_r0ckS