A brief write-up of the intended solution of P1ayground challenge from InCTF Internationals 2020

tl;dr

• Challenge is based on function hooking at runtime.
• On reversing you will find 4 functions at the same address but executing different code(basically hooked at runtime).
• Jump inside each function, reverse the algorithms to pass the checks.
• Ignore the FAKE flag check.

Intended solution of Wannavmbe challenge from InCTF Internationals 2019

tl;dr

• Challenge is a VM.
• Reverse Instruction types and implementation.
• Understand that it has a fucntion which takes the base64 of CWD (Current working directory).
• Find the corrcect directory where it needs to be placed.

tl;dr

• Challenge is a VM implemented over signals and ptrace
• Reverse Instruction types and implementation
• Use gdb scripting to find the executed code and get the pseudo VM code
• Find out the algorithm (Max triangle sum) from VM instructions
• Find an more optimized way to solve the problem (Or lazy solve it!).

tl;dr

• Challenge is a VM implemented over signals and ptrace
• Reverse Instruction types and implementation
• Use gdb scripting to find the executed code and get the pseudo VM code
• Reverse the VM functionality (Hill cipher) for flag and profit