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Analysing the worst ransomware - part 3
·8 mins
Reverse
In this part we’re going to suppose that we’ve managed to obtain a copy of the Tupper C&C server binary. Our goal is to reverse engineer it and summarize the overall operating process of Tupper.
Analysing the worst ransomware - part 2
·5 mins
Crypto
Reverse
In the last part we have seen that Tupper encrypts “.txt” files using RSA and “.pdf” files using a xor and custom key schedule. In this part we will write decryption scripts to recover encrypted files because Tupper doesn’t provide any decryption function.
Analysing the worst ransomware - part 1
·15 mins
Reverse
Today we will reverse-engineer a simple “ransomware” made specifically for this purpose. Let’s give it the name Tupper. Tupper is not really a ransomware because it doesn’t ask for a ransom, it only attacks a specific location on the filesystem and I unintentionally forgot another important feature of ransomwares, try to find it. :)
Attacking RSA for fun and CTF points - part 3
·10 mins
Crypto
Ctf
Rsa
Today the focus is on oracles ! You already encountered the decipher oracle in part 1 but now you’ll meet :
- The LSB oracle
- The padding oracle
Attacking RSA for fun and CTF points - part 2
·9 mins
Crypto
Ctf
Rsa
Before diving right into more advanced attacks, let’s take a minute to do a quick recap because it’s been a long time since the last part. Once your mind is warmed up you can safely move on.
On the program today you have :
- Small public exponent
- Hastad broadcast attack
- Fermat’s attack
- Wiener’s attack