Hurry up! Wait!

Problem

svchost.exe

• svchost.exe

Solution

1. First, I decompiled the binary using Ghidra. I then clicked though all of the functions until I came across this:

   void FUN_0010298a(void)
   
   {
       ada__calendar__delays__delay_for(1000000000000000);
       FUN_00102616();
       FUN_001024aa();
       FUN_00102372();
       FUN_001025e2();
       FUN_00102852();
       FUN_00102886();
       FUN_001028ba();
       FUN_00102922();
       FUN_001023a6();
       FUN_00102136();
       FUN_00102206();
       FUN_0010230a();
       FUN_00102206();
       FUN_0010257a();
       FUN_001028ee();
       FUN_0010240e();
       FUN_001026e6();
       FUN_00102782();
       FUN_001028ee();
       FUN_001023da();
       FUN_0010230a();
       FUN_0010233e();
       FUN_0010226e();
       FUN_001022a2();
       FUN_001023da();
       FUN_001021d2();
       FUN_00102956();
       return;
   }

2. The first function that FUN_0010298a calls is ada__calendar__delays__delay_for, which seems to create a long delay that prevents us from being able to simply run the program. However, the next functions that are called all look basically the same:

   void FUN_00102616(void)
   
   {
       ada__text_io__put__4(&DAT_00102cd8,&DAT_00102cb8,&DAT_00102cb8,&DAT_00102cd8);
       return;
   }
   
   
   void FUN_001024aa(void)
   
   {
       ada__text_io__put__4(&DAT_00102cd1,&DAT_00102cb8,&DAT_00102cb8,&DAT_00102cd1);
       return;
   }
   
   
   void FUN_00102372(void)
   
   {
       ada__text_io__put__4(&DAT_00102ccb,&DAT_00102cb8,&DAT_00102cb8,&DAT_00102ccb);
       return;
   }

3. Each function calls ada__text_io__put__4, but with different arguments. The first and last arguments differ each time ada__text_io__put__4 is invoked, but they are equal within each call.

4. Double click on DAT_00102cd8 in FUN_00102616 to see that it is p. The next global value, DAT_00102cd1, in FUN_001024aa is i. DAT_00102ccb (from FUN_00102372) is c and DAT_00102cd7 (from FUN_001025e2) is o. So, it seems that each function prints a character of the flag where each character is stored as a global variable.

5. We can double-click through each function (and go back to the calling function using the back button in Ghidra) to get the flag or a Ghidra script could be written to extract the flag, but it is faster to manually extract it.

Flag

picoCTF{d15a5m_ftw_eab78e4}