plays a similar role, it can direct location-independent function calls to absolute addresses. The link editor cannot resolve the transfer of a program from an executable file or shared library target to another execution. As a result, the connection editor can only arrange some entries containing the transfer control to the program connection table (PLT. In system V, the program connection tables are located in the shared body, but they use the addresses in the private global offset table. Dyn
is filled, the cmp [Addr] And 0xff will be used to determine whether to check the encryption option for processing. There is Magic JUMP, but the Shell API address has been redirected, and the Patch code needs to be restored.>The code is not optimized, and there is no time to optimize it. There are too many records to analyze the main program.The Patch code is as follows:Code:00B60000 60 pushad00B60001 9C pushfd00B60002 BE 00104000 mov esi, 0x401000 Code segment Addr00B60007 BF 00404000 mov edi,
, while the functionsInitbreakThe value is 004120f0, and their values are different. Why?
Just move forward and there will be an answer,
0: 000> U 41118b-8Testc! ILT + 380 (_ rtc_initialize) + 0x2:00411183 25.0e985 and eax, 85e90000h00411188 0e push CS00411189 0000 add byte PTR [eax], AlTestc! ILT + 390 (_ initbreak ):0041118b e9600f0000 JMP testc! Initbreak (004120f0)Testc! ILT + 395 (_ controlfp_s ):00411190 e987300000
to 'if (a = B) in the code ). The Cmp command indicates the subtraction operation. Therefore, it means to compare two variables. If they are not equal, jump to the memory address and print the string "a B are not equal". Otherwise, if the variables are equal, the jnz command will be skipped and the string "a B are equal" will be printed ". If multiple if statements are embedded, you will see multiple cmp, jnz, and jz, and then print strings or other operations in the future.Loop
The cyclic st
Technical Exchange, DH explanation.
I used Delphi to get the next loop body. Now let's get a conditional judgment.First, it must be the if statement we often see.
VaR I: integer; begin I: = 99; if (I> 0) and (I
What will the disassembly look like?
Project5.dpr. 12: I: = 99; 004ac44c b863000000 mov eax, $20170063project5. dpr.13: if (I> 0) and (I
here we can easily obtain the if statement structure in Delphi. Judge 1 skip ------------------------- if the condition is not met | the co
The instructions that can modify IP or cs:ip are called transfer instructions.Only modify IP, called intra-segment transfer such as JMP Ax, is divided into short transfers and near transitions based on the range of IP modifications, ranging from 128 to 127 and 32768 to 32767, respectivelySimultaneous modification of CS and IP instructions is called inter-segment transfer, such as JMP 1000:09.1 OffsetThe off
variableThere is a memory trick when EBP is not used as a universal register, that is, most of the time, when the displacement is positive, the parameters are accessed. When the displacement is negative, the local variable is accessed.Note that the typical first argument passed to a function is ebp+8② Heap VariablesHeap variables exist on the heap, and they are accessed by pointers. Typically, more than one instruction is required to access the heap variable.MOV ESI, Test2!_m_pfilelist; Load th
Implement Inline hook and inlinehook under existing software shelling ProtectionIf not, please forgive me. I am at a limited level.
Resume and level :. Http://www.cnblogs.com/hackdragon/p/3662599.htmlNormal situation:
After receiving a project to obtain the screen output content, the OD is loaded and XX shelling protection is discovered, normally, use jmp to jump to your own code and use the CHookApi_Jmp class source code used by the predecessors at h
raw binary is at offset 0, but if you need it you can change the offset to something different and make it work. forInstance the following snippet accesses the variable MSG with segment 0x7c0.
ASM example:
; boot.asm mov ax, 0x07c0 mov ds, ax mov si, msgch_loop:lodsb or al, al ; zero=end or str jz hang ; get out mov ah, 0x0E int 0x10 jmp ch_loophang: jmp hangmsg db 'Welcome to Macinto
,----------------------------get_char:mov ah,0; 16h No. 0 function, ah mid-scan code, AL in ASC II yards int 16h cmp al,0; if function key then al=0 JE K;-----Use ASCII code to judge-----------------------cmp Al,esc_key JE Exit CMP al,0dh JE Enter cmp al,board_back JE back;---read the current cursor position---------------mov ah,3 mov bh, 0 int 10h;---------------------push dx; protect variable cmp DL,WIN_LRC; Enter characters over right column value Jge NK
the Linux "Practice --2.3 program Hack20135306 HuangFirst, Master NOP , JNE , JE , JMP , CMP Machine code for assembly instructions
The NOP:NOP instruction is the "null instruction". When executing to the NOP instruction, the CPU does nothing, just as an instruction to execute the past and continue executing a command behind NOP. (Machine code: 90)
JNE: Conditional transfer directives, if not equal, jumps. (Machine code: 75)
JE: Condi
directly, the level of privilege (CPL) will only get lower, want to increase the level of privilege, can be through the task gate and other means. Here's a look at some of the things that use the task gate.First look at the case of the invocation gate in the descriptor: most notably, the door descriptor contains a selector, which, by the last experiment, can be used to move to the code snippet that the selector contains in the door task. A program calls the task door, must follow the above ment
bypassing.The actual software encryption and decryption is not that simple, but at least there is a perception thatSpeaking of cracking, I also want to talk nonsense, some learning to crack friends, anti-assembly out, modify the instructions, that the world's software will be able to crack theThe software industry is full of frustration, so let's take an example:Load a program using OD:00531001 > pushad00531002 E8 03000000 call 0053100a00531007 -E9 eb045d45
, base address addressing, variable address addressing, base address change addressing, and so on. ds:bx ss:bpds:si/di directive usage: IP cannot directly assign value call ret jmp flags Jnz:zf is not equal to 0 time transfer, that is, the previous instruction CMP ax,cx AX-CX, when the ZF is not equal to 0, then jmp to the following instruction jc:cf=1 time transfer, that is, the previous instruction oper
successful.(1) Standard Single-thread modeMethod: add Magic Jump to the breakpoint method twice. 1. Find the Magic Jump method. Method 1: run the following command: Bp GetModuleHandleA/he GetModuleHandleA/bp GetModuleHandleA 5/he GetModuleHandleA 5, and press shift f9, when the call buffer is a little large, it is generally run again after the ASCII "kernel32.dll" and ASCII "VirtualFree" appear in the stack window, and "kernel32.dll" appears, that is, the return time, cancel the breakpoint and
additional "return into libc" Check, including checking whether a return address points to the next command of call or JMP. Code of the most basic stack rollback operation (usually used in bopt), just like the following:[-----------------------------------------------------------]
While (is_valid_frame_pointer (EBP )){Ret_addr = get_ret_addr (EBP );
If (check_code_page (ret_addr) = buffer_overflow)Return buffer_overflow;
If (does_not_follow_call
1.Write code to the specified addressA, JMP address translation formula derivationB, calculate the actual address function realjmp_addrC, testing"240" JMP Instruction-Machine code--0XE9"260" instruction "JMP 88881234"--translated into machine code--"E9 88881234""328" open OD See if the JMP instructions are translated a
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