Mar
20

33C3 CTF 2016 – beeblebrox (Crypto 350)

Make bad politicians resign! nc 78.46.224.72 2048 files Summary: factorization-based attack on a signature method

Oct
15

hack you spb @ 17 Oct 2016

Remember hack you CTF? Yeah, that random event that we throw for our freshmen and everyone interested. We’re hosting a new one. It’s fall already and that means the new CTF season is starting, and so is the new academic year in the universities. This is the time when we want to attract more freshmen… Continue reading »

Oct
11

HITCON CTF QUALS 2016 – Reverse (Reverse + PPC 500)

At least our ETA is better than M$. http://xkcd.com/612/ reverse.bin Summary: optimizing an algorithm using Treap data structure and CRC32 properties.

Oct
10

HITCON CTF QUALS 2016 – PAKE / PAKE++ (Crypto 250 + 150)

pake1.rb pake2.rb Summary: attacking password-based key exchange schemes based on SPEKE with MITM.

Oct
03

TUM CTF 2016 – Shaman (Crypto 500)

Oh great shaman! Somehow the village idiot got his hands on this fancy control machine controlling things. Obviously, we also want to control things (who wouldn’t?), so we reverse-engineered the code. Unfortunately, the machine is cryptographically protected against misuse. Could you please maybe spend a few seconds of your inestimably valuable time to break that… Continue reading »

Oct
02

TUM CTF 2016 – Tacos (Crypto 400)

All my fine arts and philosophy student friends claim discrete logarithms are hard. Prove them wrong. nc 104.198.63.175 1729 vuln_tacos.py Summary: bypassing Fermat primality test with Carmichael numbers and solving discrete logarithm using Pohlig-Hellman algorithm.

Oct
02

TUM CTF 2016 – ndis (Crypto 300)

We have a HTTPS server and client talking to each other with you right in the middle! The client essentially executes curl –cacert server.crt https://nsa.gov with some magic to redirect the transmitted data to your socket, to which the server responds with a lovely German-language poem. NOTE: There is nothing else hosted on the server;… Continue reading »

Sep
19

CSAW Quals 2016 – Broken Box (Crypto 300 + 400)

I made a RSA signature box, but the hardware is too old that sometimes it returns me different answers… can you fix it for me?} e = 0x10001 nc crypto.chal.csaw.io 8002 Summary: fault attack on RSA signatures, factoring using private exponent exposure.

Sep
05

Tokyo Westerns/MMA CTF 2016 – Backdoored Crypto System (Reverse+Crypto 400)

Get the flag. bcs.7z $ nc bcs.chal.ctf.westerns.tokyo 3971 Summary: recovering AES key from partial subkey leaks.

Sep
05

Tokyo Westerns/MMA CTF 2016 – Pinhole Attack (Crypto 500)

Decrypt the cipher text with a pinhole. $ nc cry1.chal.ctf.westerns.tokyo 23464 pinhole.7z Summary: attacking RSA using decryption oracle leaking 2 consecutive bits in the middle.

May
07

CODEGATEgate

Final Scoreboard as captured by manhluat (l4w) TL;DR CTF team LC↯BC has been banned and stripped of the first place at CODEGATE CTF 2016 Finals. The fact has been announced after competition ended and even after they announced the winners. Disqualification decision was made in the most unprofessional and biased way possible, and the CTF… Continue reading »

May
03

Google CTF – Woodman (Crypto 100)

How honest are you? Running here Summary: breaking a weak PRNG

May
01

Google CTF – Spotted Wobbegong (Crypto 100)

Are you able to defeat 1024-bit RSA? public.pem Summary: breaking RSA with PCKS v1.5 padding and exponent 3.

May
01

Google CTF – Jekyll (Crypto)

Can you access the admin page? You can look at the crypto here. source.py Summary: finding a preimage for a simple 64-bit ARX-based hash.

May
01

Google CTF – Wolf Spider (Crypto 125)

Continuing on from Eucalypt Forest – can you break Message Authentication in Wolf Spider wolf.py Summary: forging signatures by exploiting CBC padding oracle and hash length extenstion

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