BUUCTF--reverse2

reverse2

1 Preprocessing
Get information
64 Bit file

2. Drag in IDA64,shift+F12
You can see directly flag, But this is not the end flag, Double click to follow up
then F5 Pseudocode found
Analyze pseudo code , Find key functions
for ( i = 0; i <= strlen(&flag); ++i )
{
if ( *(&flag + i) == 105 || *(&flag + i) == 114 )
*(&flag + i) = 49;
}
Be careful ： there 105、114、49 All are ASCII code , Reference resources ASCII The code table shows that
105 Express i 114 Express r 49 Express 1
So the final flag It's a flag Medium i and r Replace with 1.

flag{hack1ng_fo1_fun}