Where Might There Be Potential Security Vulnerabilities on Servers?
Servers, especially those exposed to the internet, can be vulnerable to various threats if not properly secured. Here are the most common areas of concern and how to mitigate them
Evans
Last Update 2 maanden geleden
❗ Risk:
Services such as Apache/Nginx, MySQL, FTP, SSH, Mail Servers (Postfix, Exim, etc.) may have vulnerabilities that attackers can exploit. Tools like nmap can easily reveal open ports and versions of services running on your server.
✅ Prevention:Keep all server software and packages regularly updated using your OS’s package manager (e.g., apt, yum, dnf).
Disable unused services to reduce the attack surface.
Subscribe to security mailing lists for software you use (e.g., Apache, MySQL).
❗ Risk:
Common platforms like WordPress, Joomla, phpBB, TYPO3, and others often allow file uploads or user input. Poor coding practices or outdated plugins/themes may open up vulnerabilities like:
File injection
Remote code execution
SQL injection
Cross-site scripting (XSS)
Always use the latest stable version of your CMS and its plugins/themes.
Remove any unused plugins/themes.
Use a Web Application Firewall (WAF) to protect against common exploits.
Limit file uploads and sanitize user inputs.
Disable execution of scripts in upload directories (e.g., using .htaccess or Nginx directives).
❗ Risk:
PHP settings can introduce security holes if not hardened. Historically vulnerable options include:
register_globals (deprecated)
safe_mode (removed in PHP 5.4)
allow_url_fopen
display_errors
Modern servers should run PHP 8.x and avoid deprecated/removed options.
Use disable_functions in php.ini to block risky functions (e.g., exec, shell_exec, system).
Run PHP using PHP-FPM with user separation or suEXEC/suPHP to isolate users.
Example secure PHP settings:
What to check if you suspect a server compromise:
Network Monitoring
Use tools like iftop, vnstat, or netstat to identify unusual traffic.
Run netstat -tulnp or ss -tuln to check for unexpected open ports.
Running Processes
Use ps aux or top to identify unfamiliar or suspicious processes.
Kill parent processes of any malicious tasks using kill -9 PID.
File Integrity
Use tools like lsattr or chattr to check and manage immutable files.
Run regular scans with tools like ClamAV, Maldet (Linux Malware Detect) or chkrootkit.
Rootkit Checks
Use rkhunter to detect known rootkits and backdoors.
Disconnect from the network to prevent further damage or spread.
Back up logs and system data for investigation.
Identify and terminate malicious processes.
Reinstall affected software or, in serious cases, rebuild the server from a clean backup.
Patch the vulnerability that led to the breach.
Change all passwords (especially for root and SSH accounts).
Use strong SSH authentication (e.g., key-based, not passwords).
Enable firewall rules (e.g., UFW, CSF, or iptables) to restrict access.
Use Fail2Ban or equivalent tools to block brute-force attempts.
Regularly audit your system and run vulnerability scans.