CVE-2020-8617 PoC — A logic error in code which checks TSIG validity can be used to trigger an assertion failure in tsig.c

Source

https://github.com/knqyf263/CVE-2020-8617

Associated Vulnerability

Title:A logic error in code which checks TSIG validity can be used to trigger an assertion failure in tsig.c (CVE-2020-8617)
Description:Using a specially-crafted message, an attacker may potentially cause a BIND server to reach an inconsistent state if the attacker knows (or successfully guesses) the name of a TSIG key used by the server. Since BIND, by default, configures a local session key even on servers whose configuration does not otherwise make use of it, almost all current BIND servers are vulnerable. In releases of BIND dating from March 2018 and after, an assertion check in tsig.c detects this inconsistent state and deliberately exits. Prior to the introduction of the check the server would continue operating in an inconsistent state, with potentially harmful results.

Description

PoC for CVE-2020-8617 (BIND)

Readme

# CVE-2020-8617
PoC for CVE-2020-8617

For educational purposes only

![demo](imgs/CVE-2020-8617.gif)

## Run
This image runs a standard BIND server, which automatically generates a tkey "local-ddns".

```
$ docker run --rm --name cve-2020-8617 -it -p 53:53/udp knqyf263/cve-2020-8617
```

## Exploit

```
$ pipenv install
$ pipenv run python exploit.py
```

## Reference
- https://kb.isc.org/docs/cve-2020-8617

## Author
Teppei Fukuda

File Snapshot


 [4.0K]  /data/pocs/3b3c1a89f413f95753cd29ef44c97772e51fcf6a
├── [4.0K]  contents
│   ├── [ 715]  example.com.signed.zone
│   ├── [ 655]  example.com.zone
│   ├── [  37]  named
│   └── [1.9K]  named.conf
├── [1.8K]  Dockerfile
├── [ 405]  exploit.py
├── [4.0K]  imgs
│   └── [7.1M]  CVE-2020-8617.gif
├── [ 11K]  LICENSE
├── [ 150]  Pipfile
├── [ 678]  Pipfile.lock
└── [ 437]  README.md

2 directories, 11 files

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