Uploaded December 2019 | Updated September 2026, 2 days ago
In theory, brute force key recovery attacks against modern ciphers like AES should be impractical with the current state of computer hardware. It's often said that recovering an AES key should take longer than the remainder of the life of the sun. However, this assumes that keys are chosen properly, and that there is no way to determine whether a key is the correct one after a candidate key is used to decrypt a captured ciphertext.
In practice, these conditions do not always hold. In much the same way that hash functions are impossible to reverse but hash cracking is still a practical attack, in the real world it is often possible to perform practical key search attacks. In this talk, we will discuss the common mistakes and common conditions that allow for practical brute force recovery of keys for modern block ciphers such as AES. We will also discuss optimizations to speed up key search efforts, and present our FOSS tool, which implements our approach.
In theory, brute force key recovery attacks against modern ciphers like AES should be impractical with the current state of computer hardware. It's often said that recovering an AES key should take longer than the remainder of the life of the sun. However, this assumes that keys are chosen properly, and that there is no way to determine whether a key is the correct one after a candidate key is used to decrypt a captured ciphertext.
In practice, these conditions do not always hold. In much the same way that hash functions are impossible to reverse but hash cracking is still a practical attack, in the real world it is often possible to perform practical key search attacks. In this talk, we will discuss the common mistakes and common conditions that allow for practical brute force recovery of keys for modern block ciphers such as AES. We will also discuss optimizations to speed up key search efforts, and present our FOSS tool, which implements our approach.
![Black Hat USA 2018 - Mainframe [z/OS] Reverse Engineering and Exploit Development](https://i.ytimg.com/vi/opBLBYAR8tU/mqdefault.jpg "Black Hat USA 2018 - Mainframe [z/OS] Reverse Engineering and Exploit Development
Speak with any Fortune 500 running mainframe and theyll tell you two things: (1) without their mainframes theyd be out of business (2) they do not conduct any security research on them, let alone vulnerability scans. The most infuriating part is that mainframes are simply computers, theyre different from what youre used to, but that doesnt mean they cant be hacked. Previous talks about this topic have covered the platform from a high level, imploring you to do the basics. This talk continues this series of talks, given by others, around mainframe hacking. Previously covered topics included network penetration testing and privilege escalation. To complement those talks, this talk will expose attendees to the various tools that exist on the platform to help you do your own reverse engineering, followed by detailed steps on how to start your own exploit development. Attendees will learn what debuggers are available on the platform, such as dbx and ASMIDF, as well as the challenges youll have using them. After learning how to RE, attendees will then learn how to develop their own exploits and buffer overflows on the platform using C, assembler and JCL. A demo program will be used to teach all these items so people can follow along. Topics included in this discussion are APF authorization, bypassing RACF/ACEE, TSO, Unix System Services.")
