InCTF 2017: stupidrop Writeup

Challenge Author: sherl0ck This challenge was originally meant to be solved using srop (SigReturn Oriented Programming). But it ended up having a bug with which it was possible to directly invoke the execve syscall. This write-up will be focusing on solving the challenge using srop. As usual, let's start off by checking the permissions of the given binary.... Continue Reading →

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InCTF 2017- GiantXOR Writeup

Author: s0rc3r3r Points: 250 Standard Encryption but can you break it? Intended Solution This challenge is a little bit tricky as compared to other crypto tasks. The text is encrypted using Repeating Key XOR, but instead of encrypting the normal plaintext, the function first encodes the message in base64 and then encrypts using Repeated Key... Continue Reading →

InCTF 2017: gryffindor pwn Writeup

Challenge Author - 4rbit3r The binary that was given was a 64-bit, dynamically linked unstripped one. Checking it's permissions - CANARY : ENABLED FORTIFY : disabled NX : ENABLED PIE : disabled RELRO : Partial Okay, nothing out of the ordinary here. The program is a standard menu driven program to add, delete and edit... Continue Reading →

InCTF 2017: warm_heap pwn Writeup

Author: 4rbit3r Hello, this was a nice challenge from InCTF 2017, let's see how to get the exploit working. As usual, running checksec on the binary gives: Nothing much here, let us look at the program itself. It is a menu driven program with some basic functionalities: Add note Edit note Remove note View note These... Continue Reading →

InCTF 2017 : sort Writeup

Author: sherl0ck This CTF was organized by bi0s itself and was the first international edition of InCTF. The binary was a 32-bit, statically linked and unstripped. Here are it's permissions - CANARY : disabled FORTIFY : disabled NX : ENABLED PIE : disabled RELRO : Partial The executable was basically implementing a bubble sort algorithm. The sort... Continue Reading →

InCTF 2017- Multi-Layer RSA writeup

Author: s0rc3r3r Points: 100 Intended Solution This is probably the easiest challenge in the Crypto section in InCTF.  The encryption script: As we can see, the encryption is layered, after the message is encrypted using the first public key i.e. first element of 'encryption_keys', the result is then encrypted with the next public key i.e.... Continue Reading →

InCTF 2017 : Browse? Writeup

Challenge created by sh1v First of thanks to Jim Shaver as the challenge was inspired from this blog. Initially we have a memory dump. On analysing it in volatility using imageinfo plugin we get to know that the memory dump is of Windows 7. Then on further analysis of the processes listed using the pslist... Continue Reading →

InCTF 2017- ‘RSA 1s Fun’ Writeup

Author: s0rc3r3r Points: 150 Mathematics and Crypto make a deadly combination! Intended Solution The challenge, as the description suggests, involves applying mathematics to solve the RSA based encryption system. The encryption code: Two different public keys e1 = 9 and e2 = 123 are being used to encrypt the same message and generate ciphertexts c1... Continue Reading →

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