Broken Chain

Vulnerability chaining is an advanced penetration testing technique where multiple lower-severity vulnerabilities are combined to achieve high-impact results. In real-world security assessments, critical findings often emerge not from a single devastating flaw but from the strategic combination of several weaknesses across different application layers. Understanding how to chain IDOR vulnerabilities, file upload exploits, and template injection attacks is essential for comprehensive security testing.

IDOR and Zip Slip: Data Access to Code Execution

Insecure Direct Object Reference (IDOR) vulnerabilities allow attackers to access resources belonging to other users by manipulating object identifiers. While IDOR alone typically leads to data disclosure, it becomes far more dangerous when the accessed data contains credentials or configuration details. Zip Slip is an archive extraction vulnerability where specially crafted ZIP files can write files to arbitrary locations on the server by including directory traversal sequences in filenames. When an application extracts uploaded archives without validating contained file paths, attackers can overwrite application code, configuration files, or web-accessible scripts.

Server-Side Template Injection (SSTI)

Server-Side Template Injection occurs when user input is embedded directly into template engine syntax rather than being passed as data. Template engines like Jinja2, Twig, and Freemarker provide powerful features - including code execution - that attackers can leverage when injection is possible. SSTI can be identified by injecting template expressions like {{7*7}} and observing whether the server evaluates them. Successful SSTI exploitation can lead to arbitrary command execution on the server, making it a critical vulnerability in web applications.

Internal Service Discovery and Lateral Movement

Enterprise environments often run internal services accessible only from the server itself. After gaining initial access, penetration testers enumerate internal ports and services that may have weaker security controls than external-facing applications. Port forwarding and tunneling techniques enable access to these internal services from the attacker's machine. Backup services, administrative panels, and database interfaces running on internal ports frequently contain additional credentials and escalation paths that lead to complete system compromise.