CVE-2021-3156 PoC — Sudo 缓冲区错误漏洞

Source

https://github.com/stong/CVE-2021-3156

Associated Vulnerability

Title:Sudo 缓冲区错误漏洞 (CVE-2021-3156)
Description:Sudo before 1.9.5p2 contains an off-by-one error that can result in a heap-based buffer overflow, which allows privilege escalation to root via "sudoedit -s" and a command-line argument that ends with a single backslash character.

Description

PoC for CVE-2021-3156 (sudo heap overflow)

Readme

# CVE-2021-3156
PoC for CVE-2021-3156 (sudo heap overflow). Exploit by @gf_256 aka cts. Thanks to r4j from super guesser for help. Credit to Braon Samedit of Qualys for the [original advisory](https://www.qualys.com/2021/01/26/cve-2021-3156/baron-samedit-heap-based-overflow-sudo.txt).

[Demo video](https://twitter.com/gf_256/status/1355354178588180481)

# Important note

**The modified time of /etc/passwd needs to be newer than the system boot time, if it isn't you can use `chsh` to update it. Unfortunately this means you will have to know the password for the account you are running as. Remember that `chsh` doesn't accept empty passwords by default so if it is empty you may have to set one with `passwd`.**

# Instructions

1. wget/curl
2. tune RACE_SLEEP_TIME
3. gcc exploit.c
4. cp /etc/passwd fakepasswd
5. modify fakepasswd so your uid is 0
6. ./a.out

Tested on Ubuntu 18.04 (sudo 1.8.21p2) and 20.04 (1.8.31)

this bug freaking sucked to PoC, it took like 3 sisyphean days and then suddenly today I just got insanely lucky

File Snapshot


 [4.0K]  /data/pocs/f53d6724f89255f1f50b60460355823e1cd73a10
├── [3.9K]  exploit.c
├── [ 973]  LICENSE
└── [1.0K]  README.md

0 directories, 3 files

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