As applications process untrusted data, injection flaws endanger systems. During development, close inspection guards against these prevalent risks. This guide outlines a methodical review process for developers to identify and fix vulnerabilities.
Understanding the Injection Threat
Injection attacks occur when unvalidated input controls an interpreter’s functions. By embedding malicious code, attackers gain unauthorized access. The OWASP Top 10 ranks injections as a primary risk. SQL, LDAP, and XSS variants frequently compromise applications.
Thoroughly vetting code mitigates these dangers. Developers must scrutinize processing of external inputs and validate all data before use. Failing to sanitize special characters allows command injection into backends like databases. Reviews identify flaws that automation can miss.
Input Validation is Key
All user-supplied content requires validation confirming proper format and length. Whitelisting accepted values blocks invalid payloads. Regular expressions validate formats for items like emails and phone numbers.
Developers must confirm validation occurs for any entry touching interpreters. Checks prevent code execution via SQL, OS commands, and other injection vectors. Parameters, cookies, headers, and other untrusted sources demand scrutiny.
Review Dynamic Queries
Dynamic SQL, NoSQL queries, and other dynamically constructed statements endanger databases. User input should never directly embed into queries.
Prepared statements solve this by separating code and data. Parameters prevent injection while improving performance versus concatenation. Reviews ensure prepared statements or similar methods properly sanitize all query parts.
Output Encoding Prevents XSS
Cross-site scripting results from displaying untrusted HTML, JavaScript, or other active code without encoding. This executes in a user’s browser under your site’s privileges.
Reviews check that all output receives contextual encoding reflecting context. HTML elements, URLs, and JavaScript strings require different encoding. Developers must validate encoding occurs for any publicly visible values.
Scrutinize Libraries and Frameworks
Externally sourced components introduce additional risk. Reviews validate that libraries properly handle injections and other flaws. If projects incorporate ORM or templating tools, developers must understand how these access databases and display output.
Frameworks abstract some security concerns but still demand caution. Reviews ensure frameworks like Django and Rails receive inputs safely and encode outputs properly. Understanding abstraction layers remains important.
Automated Scans Supplement Reviews
SAST and DAST tools identify low-hanging flaws but miss nuanced logic issues. They serve as a starting point. However, only human reviewers can understand an application’s full context. Dynamic testing also picks up bugs that static scans miss. Automation augments—rather than replaces—manual inspection.
Conclusion
Thorough code reviews catch injection vulnerabilities before deployment. Closely examining handling of untrusted data and validating all external inputs blocks exploitation. Understanding an application’s contexts enables developers to prevent attacks through informed inspection and ongoing security vigilance. Multi-layered protection at each stage of development helps secure systems against today’s prevalent injection risks.
