DirtyCred: Escalating Privilege in Linux Kernel

DirtyCred is a kernel exploitation concept that swaps unprivileged kernel credentials with privileged ones to escalate privilege. Instead of overwriting any critical data fields on kernel heap, DirtyCred abuses the heap memory reuse mechanism to get privileged. Although the concept is simple, it is effective. See the Blackhat presentation or CCS paper for more details.

Exploitation effects

Data-only: no need to bypass KASLR or leak kernel heap

Universal: the exploits written with DirtyCred would work across different kernels and architectures.

Effective: bypass all the available exploit mitigation in upstream kernel.

Demo

CVE-2021-4154

CVE-2022-2588

CVE-2022-20409 (coming soon)

Defense

See the code here.

Publication

Blackhat USA 2022

CCS 2022

Citation

@inproceedings{lin2022dirtycred,
  title={DirtyCred: Escalating Privilege in Linux Kernel},
  author={Lin, Zhenpeng and Wu, Yuhang and Xing, Xinyu},
  booktitle={Proceedings of the 2022 ACM SIGSAC Conference on Computer and Communications Security},
  pages={1963--1976},
  year={2022}
}

Online Resource

We provide two VMs for testing CVE-2022-2588. Each connection to the VM has 10 minutes timeout (i.e. the VM will be shutdown after being connected for 10 minutes). Each connection will get a fresh VM, everything stored before will be reset. When accessing the VM, please login the system with low user whose password is low. Please compile the exploit code then launch the attack.

How to connect to VMs

Please login with user low and password low

Ubuntu 20

nc 150.136.171.117 1337

Centos 8

nc 150.136.171.117 1338

Acknowledgment

This research was done with the help of Yuhang Wu and Xinyu Xing. Thanks Eduardo Vela for providing this amazing logo.