tl;dr

• Mixed mode assembly (a feature of .NET binaries), involving both C# as well as C++ code in the same executable
• Code flow jumps between both C#/C++ frequently to make analysis harder
• SEH mechanism triggered in C++ code, which uses SEH trampoline to make debugging harder
• SEH triggered once again in C#, which is handled by C++
• VM bytecode is decrypted loaded by C#
• VM checks input in 4 ways: CRC32 hash (2 byte pairs), RC4 encryption, rolling XOR and byte by byte checks

tl;dr

• Reverse to find unique function not containing bad stack canary
• Libc leak using format string vulnerability in printf
• ROP chain to get shell

tl;dr

• Analysis of eBPF assembly
• Simple optimization

tl;dr

• Custom hook to syscall 0x31337 using eBPF
• Check on the argument passed to syscall to verify correct/incorrect key

tl;dr

• This challenge is a JIT VM
• The VM logic implements modular equations

tl;dr

• This challenge comes under easy level challenge.
• The binary has a script being executed using execvp.