Take the 2-minute tour ×
Information Security Stack Exchange is a question and answer site for Information security professionals. It's 100% free, no registration required.

This article and this search suggest that the 32-bit word 0x41414141 is associated to security exploits.

Why is 0x41414141 associated to security exploits?

share|improve this question
    
Compare en.wikipedia.org/wiki/Hexspeak. My favorite is 0xDEADBEEF. –  wberry May 12 at 17:15

2 Answers 2

up vote 25 down vote accepted

It's nothing fundamental. It's just a historical convention, like using foo as the name of a variable when you have no clue what to name it.

In more detail: The simplest way to test for a buffer overflow is to type a long string of A's (AAAAAAAA...) into a text field, and see what happens. If the program crashes, it might be vulnerable. If the program crashes and a debugger shows 0x41414141 in the program counter, ooh boy, you hit pay dirt: the program is almost surely vulnerable. (Remember, the ASCII code for 'A' is 0x41 in hex, so 0x41414141 is what you'd see if you looked at the byte-level representation of a string of A's in a hex editor.)

Why A's? No reason at all; they're just the first letter in the alphabet.

So, this is a quick-and-dirty test that pentesters sometimes use. But of course, there's nothing special about 0x41414141. Douglas Adams fans could type in a long string of B's, and then look for 0x42424242. That'd be equally effective, and even more fun. I gotta remember to use that one in my next hacking demo.....

share|improve this answer
1  
I always thought it came from Aleph One's seminal paper 'Smashing the Stack for Fun and Profit' or at least was made popular by it. –  lynks Aug 15 '12 at 10:48
    
Some researchers use A's due the the matter that it is easy to count. 41 -> 1 -> A, 42 -> 2 -> B etc etc. –  Stolas Sep 30 '13 at 9:54

It's more associated with simple proof of concepts. 0x41414141 is usually the result when a (usually long) string of A's is used to demonstrate an overflow (or something similar).

share|improve this answer

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.