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Penetration Testing/Week 15/Week 15 - Buffer Overflow.md
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@@ -35,30 +35,34 @@ If source code not available:
- ESP - Stack pointer (last item on the stack)
- EBP - Stack frame base pointer and reference to arguments and local variables
- EIP - Pointer to the next instruction to execute (“instruction pointer”)
### Segment Registers
- CS : Holds the address to the Code segment of the program
- DS : Holds the address to the Data segment of the program
- SS : Holds the address to the Stack segment of the program
- CS : Holds the address to the Code segment of the program
- DS : Holds the address to the Data segment of the program
- SS : Holds the address to the Stack segment of the program
- ES,FS,GS : Hold the address to the extra segments
### Flags
- Zero Flag (ZF) - Set if the result of some instruction is zero; cleared otherwise.
- Sign Flag (SF) - Set equal to the most-significant bit of the result, which is the sign bit of a signed integer. (0 indicates a positive value and 1 indicates a negative value)
- Carry Flag (CF): Set if an arithmetic operation generate a carry or a borrow out of the most significant bit of the result, cleared otherwise
- Parity Flag (PF): Set if the least-significant byte of the result contains an even number of 1 bit, cleared otherwise.
- Overflow Flag (OF): Set if the integer result is too large a positive number or too small a negative number, excluding the sign bit, to fit in the destination operand, cleared otherwise. This flag indicates an overflow condition for signed-integer that is two’s complement arithmetic.
- Zero Flag (ZF) - Set if the result of some instruction is zero; cleared otherwise.
- Sign Flag (SF) - Set equal to the most-significant bit of the result, which is the sign bit of a signed integer. (0 indicates a positive value and 1 indicates a negative value)
- Carry Flag (CF): Set if an arithmetic operation generate a carry or a borrow out of the most significant bit of the result, cleared otherwise
- Parity Flag (PF): Set if the least-significant byte of the result contains an even number of 1 bit, cleared otherwise.
- Overflow Flag (OF): Set if the integer result is too large a positive number or too small a negative number, excluding the sign bit, to fit in the destination operand, cleared otherwise. This flag indicates an overflow condition for signed-integer that is two’s complement arithmetic.
- ![](Pasted%20image%2020250116093127.png)
### Push / Pop
PUSH src
- src operand can be a register or immediate
- In a DWORD scenario, the PUSH instruction automatically decrements the stack pointer by 4, i.e., sp <- sp-4
PUSH src
- src operand can be a register or immediate
- In a DWORD scenario, the PUSH instruction automatically decrements the stack pointer by 4, i.e., sp <- sp-4
POP src
- Src operand can be a register
- Src operand can be a register
- In a DWORD scenario, the POP instruction automatically takes a DWORD off the stack, puts in a register and increments the stack pointer by 4, i.e., sp <- sp+4
#### Examples of PUSH / POP
![](Pasted%20image%2020250116093226.png)
![](Pasted%20image%2020250116093312.png)