asm registers

[smartin77]

Hey all, I am currently reading a great article on smashing the stack. The article can be found at http://www.phrack.com/phrack/49/P49-14

Anyways, as I am reading this, I realize that I don't know much about the assembly registers that are talked about. I have searched the net and found very convoluted definitions of registers. so I was wondering if anyone could BRIEFLY talk about the following registers as they pertain to x86 systems.

eax:
ecx:
edx:
esp:
ebp:
esi:

Any help on any of these would be great!

Thanks

[smirc]

Anyways, as I am reading this, I realize that I don't know much about the assembly registers that are talked about. I have searched the net and found very convoluted definitions of registers. so I was wondering if anyone could BRIEFLY talk about the following registers as they pertain to x86 systems.

Well basically these registers are used to store values. You can move date into just about any of these registers and use them for general purpose storage. There are some exceptions to this ie. some of the registers have special properties/uses and rules to go with them.

AX or EAX: This a general purpose register but it is also used automatically for accumulator (calculator) operations like multiplication/division.

BX or EBX: Also a general purpose register but it is also used for as a base offset into sections of memory. This lets you do some nifty things with video memory for example.

CX or CBX: Also a general purpose register but it is also used as a counter in loops and stuff.

DX or EDX: Similar to AX/EAX

SP or ESP: Stack Pointer - usually only used as the current offset into the stack.

BP or EBP: Base Pointer - mostly used as an offset into the stack inside procedures

[smartin77]

smirc:
This is great information! Thank you so much for your help. Just curious, have you done any buffer overflow stuff?

-Scott

[grobyccil]

smartin, in http://www.antionline.com/showthread...hreadid=232596 u can find some links related to shellcode and buffer overflow.
ByE!
Groby

[smartin77]

Thanks for those links!

[smirc]

This is great information! Thank you so much for your help. Just curious, have you done any buffer overflow stuff?

Yes