Reversing

The hidden function This binary politely greets you when you run it, no useful string with rabin2. Running it with r2 you'll see a very simple entry0 followed by a main, yet the binary is healthy, no hlt or bad jump whatsoever. Trying afl , gave an interesting list of functions, two of which was entry1.init and entry2.fini. Seeking to them and there was a jump just before a function epilogue. ...

The "Interesting" input This binary asked for some input to generate the flag. A sym.check function shines in main: This function has 3 important parts: A check for length of the password which should be at least 0x13 or 19 characters, as shown in the figure with number 1. First four letters, indicated by 2 in the figure, implying a password starting with aqua. A for loop indicated by 3 in the figure, which is almost the most challenging (still trivial) part. ...