Stack cookie verifier


void __fastcall FUN_00401ccb(int param_1)

{
  if (param_1 == DAT_00411018) {
    return;
  }
  FUN_00401d32();
  return;
}


Boom. There it is — the stack cookie verifier in action.

void __fastcall FUN_00401ccb(int param_1)  {    if (param_1 == DAT_00411018) {      return;    }    FUN_00401d32();    return;  }

🔍 What's It Doing?

  • DAT_00411018 is your stack cookie — a value placed on the stack to detect corruption (like from buffer overflows).

  • param_1 is the runtime-computed value, usually something like:

    uVar1 = DAT_00411018 ^ (uint)&stack_variable;

  • At the end of a function, the code reverses the XOR to verify the cookie.

  • If the values don't match, that means:

    • Stack overflow

    • Memory corruption

    • Or malicious tampering

→ So it jumps to FUN_00401d32().

💣 What's in FUN_00401d32()?

Almost definitely:

  • A crash

  • A call to __report_gsfailure() or TerminateProcess

  • Possibly a call to RaiseException() with a fatal error code

This is classic GS (Guard Stack) cookie handling from the Visual Studio compiler's /GS protection.

✅ TL;DR

Function Role
FUN_00401ccb Validates the stack cookie to detect stack smashing
DAT_00411018 The expected cookie value
param_1 The runtime-calculated cookie check
FUN_00401d32() Gets called on mismatch → likely crashes immediately

Want to confirm what FUN_00401d32() does? Paste it in — let's finish mapping the full stack guard path 🔒💥


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