[Juniors CTF 2016] [Trivial admin 400 – ROFL] Write UpDescription
No description, only a PDF embedded file containing 73 pages:
Vm0wd2QyUXlVWGxWV0d4V1YwZDRWMVl3WkRSV01WbDNXa1JTVjAxV2JETlhhMUpUVmpBeFYySkVU
bGhoTVVwVVZtcEJlRll5U2tWVQpiR2hvVFZWd1ZWWnRjRUpsUmxsNVUydFdWUXBpUjJodlZGWldk
MVpXV25SalJVcHNVbXhzTlZVeWRGZFdVWEJwVWpKb2RsWkdXbGRrCk1WcFhWMjVTYWxKVmNITlZi
[…]
M0JYVFc1b1dGWnFSbHBsUm5CR1lVWlNhV0pGV2sxV2ExSkhWVEZSZUZkc1drNEtWbTFTV1ZscgpW
a3RaVm14ellVYzVVMUpzY0hwV2JHaHZWVEpLVmsxVVRscGxhMG8yVlROa2RsQlJiejBLCg==
Resolution
As you can see it’s a LOOOOOOOONG string in base64.
We put this string into a file named “1” and run this bash script:
for i in `seq 1 34`; do file="`cat $i`" ; ((i++)) ; echo $file | tr -d '\n' | base64 -d > $i ; done
Our files contained:
#33: 6Mn2yc7hX971xMXza #34: èÉöÉÎá_ÞõÄÅó
Charset error! There’s no accents like this in Russian 🙁
We used http://www.charset.ru/ to retrieve all possible combinations:
иЙцЙОб_ЮхДЕу ХиЖинА_чУдеС ЙкГкпВ_аИдеХ
Flag was ХиЖинА_чУдеС
You can just use decode function in Python with ‘koi8-r’ as first argument in it and don’t use brute in flag field 😉
You’re right! An admin gave the hint of “koi8-r” after we solved it 🙁