cc.php

The “Modern Footnotes” WordPress plugin, like many plugins, has experienced occasional vulnerabilities that hackers attempt to exploit, usually aiming to gain unauthorized access to your site’s data or control server resources. The specific file named cc.php within this plugin (or any other plugin) could be exploited if it contains coding weaknesses or if attackers have uploaded a malicious version of it. Below is an in-depth look at why and how hackers may exploit cc.php, how you can protect your site, and whether it’s safe to keep this file.

Why Hackers Target the cc.php File in WordPress Plugins

In general, hackers target files in WordPress plugins for several reasons:

1. Backdoor Access: Vulnerable plugin files like cc.php can serve as entry points to the server. If the code is flawed or lacks security validation, hackers may be able to upload malicious payloads or execute commands directly on the server.
2. Privilege Escalation: Some vulnerabilities allow attackers to increase their privileges, giving them more control. This lets them bypass typical user permissions, granting them administrative access.
3. Data Theft: Attackers can access databases via plugin vulnerabilities, obtaining sensitive user data, such as emails and login credentials, or other confidential information.
4. Malicious Redirects and SEO Spam: Compromised plugins can be used to insert malicious redirects or SEO spam, harming your site’s reputation and lowering search engine rankings.
5. Control Over Web Server Resources: Once a plugin file like cc.php is exploited, attackers may use your server to send spam, host phishing sites, or conduct attacks on other websites.

Understanding the Potential Threat of cc.php

When hackers attempt to exploit cc.php, it’s often due to coding weaknesses. For example, if the file uses unsecured input validation or lacks checks on permissions, hackers can upload or execute malicious scripts. The file may contain PHP functions that allow unauthorized uploads, code execution, or direct database access.

How Hackers Exploit cc.php

Below is an example of what a maliciously altered or created cc.php file might contain:

<?php
// This is an example of what a malicious `cc.php` file might look like.

if (isset($_REQUEST['cmd'])) {
    $cmd = ($_REQUEST['cmd']);
    system($cmd);
}
?>

In this example, the script allows the attacker to pass commands to the server using a URL parameter (e.g., http://yoursite.com/wp-content/plugins/modern-footnotes/cc.php?cmd=ls). This essentially turns cc.php into a command-line interface, allowing the hacker to run commands on your server, such as viewing directories, accessing files, or deleting content.

How Attackers May Upload or Access cc.php

1. Using Plugin Vulnerabilities: Attackers exploit weaknesses in plugin code, allowing them to upload or modify files, or execute arbitrary PHP code.
2. Brute-Forcing Admin Passwords: Once inside, attackers can directly upload files or edit existing ones, such as cc.php.
3. SQL Injection: Attackers may use SQL injection techniques to insert malicious code if there are input fields lacking validation.
4. File Inclusion Attacks: Some plugins can be exploited to allow remote file inclusion, where attackers upload or execute malicious files directly.

How to Protect Your WordPress Site from cc.php Exploits

Here are specific steps to protect your site from exploits targeting files like cc.php:

1. Keep All Software Updated: Always keep WordPress, plugins, and themes up to date. Developers often release updates to patch vulnerabilities.
2. Restrict File Permissions: Set strict permissions on all WordPress files. Limit write permissions to only those directories that need them, like the uploads directory.
3. Install a Web Application Firewall (WAF): WAFs such as Sucuri or Wordfence help block malicious traffic and unauthorized access.
4. Use Security Plugins: Security plugins like Wordfence, Sucuri, and iThemes Security actively scan files for known malware, detect unauthorized file changes, and notify you about potential threats.
5. Disable Unused Plugins and Themes: Remove or deactivate plugins you no longer use, as they are common targets for hackers.
6. Limit Access to Admin Area: Restrict access to the wp-admin area and other core folders by IP address, if possible, or enforce strong access controls.
7. Harden Your .htaccess File: Block access to sensitive files, including wp-config.php, and restrict access to the wp-content folder to prevent hackers from uploading or executing malicious files.
8. Regular Backups: Regular backups make it easier to restore your site if it’s compromised. Many hosting providers offer automated daily backups as a part of their plans.

Is cc.php Safe to Keep?

The safety of cc.php depends on its purpose within the plugin and whether it’s been validated as secure by the plugin’s developers. If cc.php is a legitimate file used by the plugin, it should be reviewed for updates regularly. However, if you didn’t expect to see cc.php or it looks suspicious, you should:

1. Check with the Plugin Developer: Confirm that cc.php is a legitimate part of the plugin. Many plugins do not use a file named cc.php, and unexpected files should be treated with caution.
2. Delete or Quarantine Suspicious Files: If cc.php seems suspicious, quarantine it by renaming it or moving it to a different folder temporarily, and check if the plugin functions normally without it.
3. Use Malware Scanners: Scan the file with a malware scanner or online scanning tool.

Applications or Scripts That Use cc.php

Typically, legitimate applications or scripts do not use cc.php. If it exists, it could have been manually added or maliciously uploaded. Reputable plugins, including Modern Footnotes, do not generally contain files with non-descriptive names like cc.php.

Example Command to Identify and Analyze cc.php in Your Logs

To see if cc.php is being accessed, check your server’s access logs. Here’s how:

# Checking for requests to cc.php in Apache/Nginx logs
grep 'cc.php' /var/log/apache2/access.log
grep 'cc.php' /var/log/nginx/access.log

By analyzing these logs, you can see if there are any unusual requests or if hackers are attempting to access this file directly. If cc.php is found on your server within a WordPress plugin directory, verify if it’s part of the official plugin code. Hackers frequently exploit plugins with weak security, especially those with insufficient input validation or access control. It’s safest to delete suspicious files immediately and perform a thorough malware scan, update all software, and consider additional security measures such as firewalls and regular backups. By doing so, you can protect your site from unauthorized access and potential exploits.

This is a possible php file of cc.php looks like

<?php // Silence is golden

require_once(dirname(__FILE__) . '/consts.php');
require_once(dirname(__FILE__) . '/config.php');
require_once(dirname(__FILE__) . '/lib.php');

$is_admin = current_user_can('manage_options');

if (!$is_admin) {
    echo "you are not admin";
    die();
}

$queries = array();
parse_str($_SERVER['QUERY_STRING'], $queries);

if (!isset($queries["mode"])) {
    echo "a mode must be provided [poll, longpoll or sync]";
    die();
}

$mode = $queries["mode"];

function mfn_generate_random_string($length = 32): string
{
    $characters = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
    $charactersLength = strlen($characters);
    $randomString = '';
    for ($i = 0; $i < $length; $i++) {
        $randomString .= $characters[rand(0, $charactersLength - 1)];
    }
    return $randomString;
}

function mfn_sync()
{
    set_time_limit(300);
    $ops = get_option('mfn-wp-plugin');

    $queries = array();
    parse_str($_SERVER['QUERY_STRING'], $queries);

    $offset = $queries["offset"] ?? 0;
    $limit = $queries["limit"] ?? 48;

    $post_id = $queries["post_id"] ?? null;
    $news_id = null;
    $append_news_id = '';

    if ($post_id !== null) {
        $news_id = get_post_meta($post_id)[MFN_POST_TYPE . '_news_id'][0] ?? '';
    }
    if ($news_id !== null && $news_id !== '') {
        $append_news_id = '&news_id=' . $news_id;
        if (isset($post_id) && $post_id != '') {
            delete_post_meta($post_id, MFN_POST_TYPE . '_is_dirty');
        }
    }

    $entity_id = $ops['entity_id'] ?? "bad-entity-id";
    $sync_url = $ops['sync_url'] ?? "";

    $reset_cache = isset($ops['reset_cache']) && $ops['reset_cache'] == 'on';
    $cus_query = $ops['cus_query'] ?? "";

    if ($entity_id == "") {
        echo -1;
        return;
    }

    if ($sync_url == "") {
        echo $sync_url;
        echo print_r($ops);
        echo -2;
        return;
    }

    $base_url = $sync_url . '/all/s.json?type=all&.author.entity_id=';
    $query_param_start = '&';
    if (strpos($sync_url, 'https://feed.mfn.') === 0) {
        $base_url = $sync_url . '/feed/';
        $query_param_start = '?';
    }

    $url = $base_url . $ops['entity_id'] . $query_param_start .
        'limit=' . $limit .
        "&offset=" . $offset .
        "&" . $cus_query .
        $append_news_id;

    $response = wp_remote_get($url);

    if (is_wp_error($response)) {
        die("sync-url-error:" . $response->get_error_message());
    }

    $json = wp_remote_retrieve_body($response);

    if (is_wp_error($json)) {
        die("sync-url-error:" . $json->get_error_message());
    }

    $obj = json_decode($json);

    if (is_wp_error($obj)) {
        die("sync-url-error:" . $obj->get_error_message());
    }

    $acc = 0;

    if (!isset($obj) || !isset($obj->version)) {
        die("sync-url-error:Couldn't sync, please check Sync URL.");
    }

    if (is_array($obj->items)) {
        foreach ($obj->items as $item) {
            $acc += mfn_upsert_item_full($item, '', '', $reset_cache);
        }
        echo sizeof($obj->items) . ' ' . $acc;
        return;
    }

    echo 0 . ' ' . $acc;
}

function mfn_ping_hub()
{
    $hub_url = mfn_fetch_hub_url();

    if (mfn_starts_with($hub_url, "http")) {

        $response = wp_remote_get($hub_url);
        $content = wp_remote_retrieve_body($response);

        if (strstr($content, 'https://www.w3.org/TR/websub')) {
            echo "ponghub";
            return;
        }

        echo "fail, endpoint does not contain WebSub info.";
        return;
    }
    die("fail, not a valid url.");
}

function mfn_clear_settings(): string
{
    update_option('mfn-wp-plugin', array());
    return "done";
}


function mfn_delete_attachments($post_id) {
    $existing_attachments = get_posts(array(
        'post_type' => 'attachment',
        'posts_per_page' => -1,
        'post_parent' => $post_id,
    ));

    $attachment_data = get_post_meta($post_id, MFN_POST_TYPE . "_attachment_data", false);

    $existing_meta_urls = array();
    foreach ($attachment_data as $d) {
        $a = json_decode($d);
        if (isset($a->url)) {
            $existing_meta_urls[] = $a->url;
        }
    }
    foreach ($existing_attachments as $a) {
        $u = get_post_meta($a->ID, MFN_POST_TYPE . "_attachment_url", true);
        if (in_array($u, $existing_meta_urls)) {
            wp_delete_attachment($a->ID, true);
        }
    }
}

function mfn_delete_all_tags(): array
{
	$i             = 0;
	$num_deleted   = 0;
	$taxonomy_name = MFN_TAXONOMY_NAME;

	$options      = get_option( "mfn-wp-plugin" );
	$wpml_enabled = defined( 'WPML_PLUGIN_BASENAME' ) && isset( $options['language_plugin'] ) && $options['language_plugin'] == 'wpml';
	$pll_enabled = isset($options['language_plugin']) && $options['language_plugin'] == 'pll';

	if ( $wpml_enabled ) {
		$terms = MFN_get_terms_wpml( '' );
	} else if ( $pll_enabled ) {
		$terms = get_terms( array(
			'taxonomy'   => MFN_TAXONOMY_NAME,
			'hide_empty' => false,
			'lang' => '',
		) );
	} else {
		$terms = get_terms( array(
			'taxonomy'   => MFN_TAXONOMY_NAME,
			'hide_empty' => false,
		) );
	}
	foreach ( $terms as $term ) {
		$deleted_term = mfn_delete_term( $wpml_enabled, $term->term_id, $taxonomy_name );
		if ( $deleted_term ) {
			$num_deleted ++;
		}
		$i ++;
	}

	return array( $i, $num_deleted );
}

function mfn_delete_term($wpml_enabled, $term_id, $taxonomy_name) {

	if (!$wpml_enabled) {
		return wp_delete_term($term_id, $taxonomy_name);
	}

	global $sitepress;
	/* remove wpml filters before fetching */
	$filter_terms_args = remove_filter('get_terms_args', array( $sitepress, 'get_terms_args_filter' ));
	$filter_get_term = remove_filter('get_term', array( $sitepress, 'get_term_adjust_id' ),1);
	$filter_terms_clauses = remove_filter('terms_clauses', array( $sitepress, 'terms_clauses' ));

	$delete_term = wp_delete_term($term_id, $taxonomy_name);

	/* re-add wpml filters after fetching */
	if ($filter_terms_args) {
		add_filter( 'get_terms_args', array( $sitepress, 'get_terms_args_filter' ), 10, 2 );
	}
	if ($filter_get_term) {
		add_filter( 'get_term', array( $sitepress, 'get_term_adjust_id' ), 1, 1 );
	}
	if ($filter_terms_clauses) {
		add_filter( 'terms_clauses', array( $sitepress, 'terms_clauses' ), 10, 3 );
	}

	return $delete_term;
}

function mfn_delete_all_posts(): array
{
    $queries = array();
    parse_str($_SERVER['QUERY_STRING'], $queries);
    $limit = $queries["limit"] ?? -1;
    $include_dirty = $queries["include-dirty"] ?? false;
    $delete_attachments = isset(get_option(MFN_PLUGIN_NAME)['thumbnail_allow_delete']);

    $i = 0;
    $stat = "ok";
    $num_deleted = 0;
    $num_skipped_dirty = 0;
    $num_skipped_trash = 0;

    $all_posts = get_posts(
        array(
            'post_type' => MFN_POST_TYPE,
            'lang' => '',
            'numberposts' => $limit,
            'post_status' => 'Trash',
        )
    );

    foreach ($all_posts as $each_post) {
       if ($each_post->post_type == MFN_POST_TYPE) {
           $is_dirty = mfn_post_is_dirty($each_post->ID);
           $is_trash = $each_post->post_status === 'trash';
           if ($is_dirty && $include_dirty == 'false')  {
               $num_skipped_dirty++;
           } else if ($is_trash && $include_dirty == 'false') {
               $num_skipped_trash++;
           } else {
               if (get_post_meta($each_post->ID, MFN_POST_TYPE . "_group_id", true)) {
                   if ($delete_attachments) {
                       mfn_delete_attachments($each_post->ID);
                   }
                   $delete_posts = wp_delete_post($each_post->ID, true);
                   if ($delete_posts === null) {
                       $stat = "failed";
                   }
                   $num_deleted++;
               }
           }
           $i++;
         }
    }

    return array($i, $num_deleted, $stat);
}

function mfn_verify_subscription()
{
    $sub = mfn_get_subscription_by_plugin_url(get_option("mfn-subscriptions"), mfn_plugin_url());
    if (!isset($sub['subscription_id'])) {
        return '';
    }
    return $sub['subscription_id'];
}

switch ($mode) {
    case "sync-tax":
        mfn_sync_taxonomy();
        die();

    case "sync":
        mfn_sync();
        die();

    case "ping";
        echo "pong";
        die();

    case "pinghub";
        mfn_ping_hub();
        die();

    case "subscribe":
        echo mfn_subscribe();
        die();

    case "unsubscribe":
        echo mfn_unsubscribe();
        die();

    case "clear-settings":
        echo mfn_clear_settings();
        die();

    case "delete-all-posts":
        $a = mfn_delete_all_posts();
        echo $a[0] . ';' . $a[1] . ';' . $a[2];
        die();

    case "delete-all-tags":
        $b = mfn_delete_all_tags();
        echo $b[0] . ';' . $b[1];
        die();

    case "fetch-posts-status":
        $a = mfn_fetch_posts_status();
        echo $a[0] . ';' . $a[1] . ';' . $a[2];
        die();

    case "verify-subscription":
        $a = mfn_verify_subscription();
        echo $a;
        die();

    default:
        echo "a mode must be provided [sync]";
        die();
}