# House of Lore | Small bin Attack

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## Basic Information

### Code

* Check the one from [https://ctf-wiki.mahaloz.re/pwn/linux/glibc-heap/house\_of\_lore/](https://ctf-wiki.mahaloz.re/pwn/linux/glibc-heap/house\_of\_lore/)
  * This isn't working
* Or: [https://github.com/shellphish/how2heap/blob/master/glibc\_2.39/house\_of\_lore.c](https://github.com/shellphish/how2heap/blob/master/glibc\_2.39/house\_of\_lore.c)
  * This isn't working even if it tries to bypass some checks getting the error: `malloc(): unaligned tcache chunk detected`
* This example is still working: [**https://guyinatuxedo.github.io/40-house\_of\_lore/house\_lore\_exp/index.html**](https://guyinatuxedo.github.io/40-house\_of\_lore/house\_lore\_exp/index.html)&#x20;

### Goal

* Insert a **fake small chunk in the small bin so then it's possible to allocate it**.\
  Note that the small chunk added is the fake one the attacker creates and not a fake one in an arbitrary position.

### Requirements

* Create 2 fake chunks and link them together and with the legit chunk in the small bin:
  * `fake0.bk` -> `fake1`
  * `fake1.fd` -> `fake0`
  * `fake0.fd` -> `legit` (you need to modify a pointer in the freed small bin chunk via some other vuln)
  * `legit.bk` -> `fake0`

Then you will be able to allocate `fake0`.

### Attack

* A small chunk (`legit`) is allocated, then another one is allocated to prevent consolidating with top chunk. Then, `legit` is freed (moving it to the unsorted bin list) and the a larger chunk is allocated, **moving `legit` it to the small bin.**
* An attacker generates a couple of fake small chunks, and makes the needed linking to bypass sanity checks:
  * `fake0.bk` -> `fake1`
  * `fake1.fd` -> `fake0`
  * `fake0.fd` -> `legit` (you need to modify a pointer in the freed small bin chunk via some other vuln)
  * `legit.bk` -> `fake0`
* A small chunk is allocated to get legit, making **`fake0`** into the top list of small bins
* Another small chunk is allocated, getting `fake0` as a chunk, allowing potentially to read/write pointers inside of it.

## References

* [https://ctf-wiki.mahaloz.re/pwn/linux/glibc-heap/house\_of\_lore/](https://ctf-wiki.mahaloz.re/pwn/linux/glibc-heap/house\_of\_lore/)
* [https://heap-exploitation.dhavalkapil.com/attacks/house\_of\_lore](https://heap-exploitation.dhavalkapil.com/attacks/house\_of\_lore)
* [https://guyinatuxedo.github.io/40-house\_of\_lore/house\_lore\_exp/index.html](https://guyinatuxedo.github.io/40-house\_of\_lore/house\_lore\_exp/index.html)

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