cmpsb is used to compare 2 sequences of bytes. It subtracts value at EDI from ESI and updates the flags. Cmpsb takes byte at ESI, compares to value at EDI and increments ESI/EDI registers by 1. Bundling this with rep is equivalent to memcmp in C.
IDA Pro 7.2 Leaked Update keygen
By taking a look at what we know, we can examine the binary in question within IDA and see it creates a kernel service which is then used to stealthily update the registry to disable the Windows Firewall before being unloaded.
In this instance 3 options cause a subroutine to be called, whereas one just updates a variable which is then used to quit the C2 loop and thus the program. The possible subroutines and their associated trigger letter are shown below. 2ff7e9595c