Assembly for Reverse Engineering

These are some assembly instructions to do reverse engineering more easy:

• MOV (Move): Copies the value from one location to another.

mov eax, 42     ; Move the value 42 into the eax register

• ADD: Adds two values.

add ebx, eax    ; Add the value in eax to the value in ebx

• SUB: Subtracts one value from another.

sub ecx, edx    ; Subtract the value in edx from the value in ecx

• CMP (Compare): Compares two values and sets flags based on the result.

cmp esi, edi    ; Compare the values in esi and edi and set flags accordingly

• JMP (Jump): Unconditionally transfers control to another instruction.

jmp label       ; Unconditionally jump to the location labeled "label"

• JE (Jump if Equal): Jumps to a specific location if the zero flag is set.

je equal_label  ; Jump to "equal_label" if the zero flag is set (previous comparison was equal)

• JNE (Jump if Not Equal): Jumps to a specific location if the zero flag is not set.

jne not_equal_label  ; Jump to "not_equal_label" if the zero flag is not set (previous comparison was not equal)jz label       ; Jump to "label" if the zero flag is set (eax == 0)

• JZ: It's a conditional jump instruction that transfers program control to a specified label or memory location if the zero flag (ZF) is set.

jz label       ; Jump to "label" if the zero flag is set (eax == 0)

• CALL: Calls a subroutine or function.

call my_function  ; Call the subroutine or function labeled "my_function"

• RET (Return): Returns from a subroutine.

ret            ; Return from a subroutine

• PUSH: Pushes a value onto the stack.

push eax       ; Push the value in eax onto the stack

• POP: Pops a value from the stack.

pop ebx        ; Pop a value from the stack into the ebx register

• AND, OR, XOR: Performs logical AND, OR, and XOR operations on values.

and edx, ebx   ; Perform bitwise AND between edx and ebx
or ecx, eax    ; Perform bitwise OR between ecx and eax
xor esi, edi   ; Perform bitwise XOR between esi and edi

• SHL/SHR (Shift Left/Right): Shifts bits left or right.

shl eax, 2     ; Shift the bits in eax left by 2 positions
shr ebx, 1     ; Shift the bits in ebx right by 1 position

• INC/DEC (Increment/Decrement): Increases or decreases a value by one.

inc ecx        ; Increment the value in ecx by one
dec edx        ; Decrement the value in edx by one

• LOOP: Decrements a counter and jumps if the counter is not zero.

mov ecx, 5     ; Set ecx to 5 (loop counter)
loop loop_label ; Decrement ecx and jump to "loop_label" while ecx is not zero

• NOP (No Operation): Does nothing and acts as a placeholder.

nop            ; No operation, does nothing

• INT (Interrupt): Triggers an interrupt or software-generated exception.

int 0x80       ; Trigger a software interrupt (Linux system call)

• LEA (Load Effective Address): Loads the address of a memory location.

lea ebx, [ecx+edx]  ; Load the effective address of ecx+edx into ebx

• CMPXCHG (Compare and Exchange): Compares and swaps a value if conditions are met (used in multi-threading).

cmpxchg [eax], ebx  ; Compare the value in eax with the value at the memory address pointed by eax and exchange with ebx if equal (used in multi-threading)

• XOR: Performs bitwise XOR on two values.

xor eax, eax   ; Clear the eax register by XORing it with itself