File Upload Attacks
Summary
File Upload Attacks involve malicious actors uploading harmful files to a target system, often to execute unauthorized code, steal data, or compromise application integrity. These attacks exploit vulnerabilities in file upload functionalities within web applications or services, allowing attackers to bypass security controls and gain unauthorized access or execute arbitrary commands.
Key Characteristics
- Exploitation of file upload features to deliver malware or scripts.
- Use of disguised file types or double extensions to evade detection.
- Execution of server-side code through uploaded files, such as web shells.
- Potential for privilege escalation and data exfiltration.
- Common in web applications lacking proper validation and sanitization.
Defensive Controls
- Implement strict file type validation and allowlist acceptable file formats.
- Enforce file size limits and scan uploads with antivirus software.
- Use server-side checks to verify file content and metadata.
- Store uploaded files outside the webroot to prevent direct execution.
- Apply least privilege principles to file upload directories and services.
- Employ input sanitization and content security policies.
Related Security Solutions
Web Application Firewalls (WAFs) can help detect and block malicious file uploads. Antivirus and endpoint protection solutions scan and quarantine harmful files. Secure coding practices and runtime application self-protection (RASP) tools enhance resilience against file upload exploits. Content Delivery Networks (CDNs) with security features may also mitigate attack impact.