Description
During an autit, you found these files and those commands:
$ dd if=/dev/urandom of=key.bin bs=16 count=1
$ ./esc -e < stereogram.png > stereogram.png.enc
$ ./esc < stereogram.png
[>] Done encrypting 1280731 bytes.
[2] 11735 segmentation fault ./esc < stereogram.png
It seems that this crash has been exploited: can you figure out how and read flag.txt?
You don’t have key.bin, but the service provided gives access to esc (without arguments) using the same key.bin file as the one generated by the above command.
Files
- docker-compose.yml
-
esc
14.04 KiB – a3c4ac10a1dc8ee30efc803050686ccb9513e2156de0a9108a53f3d153a1ee69 -
stereogram.png
1.22 MiB – 65bcaaedd01a54d6c90e078c5434a84d2924fb967cd062f7b9d7084947c7342b -
stereogram.png.enc
1.22 MiB – 44d181ae214355485af345f844bfaf22d3f991b61da58655f1afd05c0cdf0af7
Author
Challenge Instructions
- First, download docker-compose.yml:
curl https://hackropole.fr/challenges/fcsc2021-pwn-encrypted-shellcode/docker-compose.public.yml -o docker-compose.yml - Launch the challenge by executing in the same folder:
docker compose up - Then, in another console, access the challenge with Netcat:
nc localhost 4000
In case you encounter problems, please consult the FAQ.
Flag
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