我正在尝试制作缓冲区利用示例（来自http://insecure.org/stf/smashstack.html的 example3.c) 在 Debian Lenny 2.6 版本上工作。我知道 gcc 版本和操作系统版本与 Aleph One 使用的版本不同。我使用 -fno-stack-protector 和 sysctl -w kernel.randomize_va_space=0 参数禁用了任何堆栈保护机制。为了解释我的设置和 Aleph One 的差异，我引入了两个参数：offset1 -> 从 buffer1 变量到返回地址的偏移量和 offset2 -> 要跳转多少字节以跳过语句。我试图通过分析汇编代码找出这些参数，但没有成功。因此，我编写了一个 shell 脚本，它基本上运行缓冲区溢出程序，同时具有来自 (1-60) 的 offset1 和 offset2 值。但令我惊讶的是，我仍然无法打破这个程序。如果有人可以指导我，那就太好了。我附上了代码和汇编输出以供考虑。对不起，很长的帖子：）
谢谢。
// Modified example3.c from Aleph One paper - Smashing the stack
void function(int a, int b, int c, int offset1, int offset2) {
char buffer1[5];
char buffer2[10];
int *ret;
ret = (int *)buffer1 + offset1;// how far is return address from buffer ?
(*ret) += offset2; // modify the value of return address
}
int main(int argc, char* argv[]) {
int x;
x = 0;
int offset1 = atoi(argv[1]);
int offset2 = atoi(argv[2]);
function(1,2,3, offset1, offset2);
x = 1; // Goal is to skip this statement using buffer overflow
printf("X : %d\n",x);
return 0;
}
-----------------
// Execute the buffer overflow program with varying offsets
#!/bin/bash
for ((i=1; i<=60; i++))
do
for ((j=1; j<=60; j++))
do
echo "`./test $i $j`"
done
done
-- Assembler output
(gdb) disassemble main
Dump of assembler code for function main:
0x080483c2 <main+0>: lea 0x4(%esp),%ecx
0x080483c6 <main+4>: and $0xfffffff0,%esp
0x080483c9 <main+7>: pushl -0x4(%ecx)
0x080483cc <main+10>: push %ebp
0x080483cd <main+11>: mov %esp,%ebp
0x080483cf <main+13>: push %ecx
0x080483d0 <main+14>: sub $0x24,%esp
0x080483d3 <main+17>: movl $0x0,-0x8(%ebp)
0x080483da <main+24>: movl $0x3,0x8(%esp)
0x080483e2 <main+32>: movl $0x2,0x4(%esp)
0x080483ea <main+40>: movl $0x1,(%esp)
0x080483f1 <main+47>: call 0x80483a4 <function>
0x080483f6 <main+52>: movl $0x1,-0x8(%ebp)
0x080483fd <main+59>: mov -0x8(%ebp),%eax
0x08048400 <main+62>: mov %eax,0x4(%esp)
0x08048404 <main+66>: movl $0x80484e0,(%esp)
0x0804840b <main+73>: call 0x80482d8 <printf@plt>
0x08048410 <main+78>: mov $0x0,%eax
0x08048415 <main+83>: add $0x24,%esp
0x08048418 <main+86>: pop %ecx
0x08048419 <main+87>: pop %ebp
0x0804841a <main+88>: lea -0x4(%ecx),%esp
0x0804841d <main+91>: ret
End of assembler dump.
(gdb) disassemble function
Dump of assembler code for function function:
0x080483a4 <function+0>: push %ebp
0x080483a5 <function+1>: mov %esp,%ebp
0x080483a7 <function+3>: sub $0x20,%esp
0x080483aa <function+6>: lea -0x9(%ebp),%eax
0x080483ad <function+9>: add $0x30,%eax
0x080483b0 <function+12>: mov %eax,-0x4(%ebp)
0x080483b3 <function+15>: mov -0x4(%ebp),%eax
0x080483b6 <function+18>: mov (%eax),%eax
0x080483b8 <function+20>: lea 0x7(%eax),%edx
0x080483bb <function+23>: mov -0x4(%ebp),%eax
0x080483be <function+26>: mov %edx,(%eax)
0x080483c0 <function+28>: leave
0x080483c1 <function+29>: ret
End of assembler dump.