How to find security vulnerabilities in source code

Source code refers to the original form of a software program and consists of human-readable instructions written in a specific programming language. A software’s source code commonly includes custom code written by a developer, open source packages and containers, and infrastructure as code (IaC) which are scripts and configuration files used to manage and provision cloud infrastructure. 

Source code should be assessed for security vulnerabilities early in the development cycle to catch potential problems before they become costly to remediate. In this article, we’ll detail how to find and fix security vulnerabilities in your source code. 

Perform a code review

To ensure the security and reliability of your software, it’s best practice to perform a code review of the first-party, custom code written by developers. This entails examining and analyzing various aspects of the code, including its design, architecture, coding style, and documentation. 

Identify common vulnerabilities 

When conducting your code review, it’s important to look for potential security vulnerabilities that bad actors could exploit. 

Common vulnerabilities include:

• Cross-site request forgery (CSRF): A vulnerability that allows an attacker to deceive a user into performing an unintended action while on a website.

• Insecure password storage: A vulnerability whereby passwords are stored in readily accessible plain text or in a format that bad actors can easily reverse.

• Insufficient input validation: a vulnerability whereby user inputs are not properly validated, resulting in various security issues.

Identify injection vulnerabilities 

Code reviewers should also assess source code for injection vulnerabilities. This type of security vulnerability occurs when untrusted data is sent to an application without proper validation or sanitization. An injection vulnerability allows a bad actor to inject malicious code or commands into the application.

Common injection vulnerabilities include:

• SQL injection: A technique where an attacker injects malicious SQL code into an application's database query, permitting them to read, modify, or delete data from the database.

• Command injection: A technique where an attacker can inject malicious commands into an application's command-line interface or shell, permitting them to execute arbitrary code on the server.

• Cross-site scripting (XSS) injection: A technique where an attacker can inject malicious scripts into a web page viewed by other users, permitting them to steal sensitive data or perform other malicious actions.

• LDAP injection: A technique where an attacker can inject malicious LDAP statements into an application's LDAP query, permitting them unauthorized access to the LDAP directory or the ability to perform other malicious actions.

• XML injection: A technique where an attacker can inject malicious XML data into an application's XML parser, permitting them to read, modify, or delete data from the XML file.

To ensure security, developers should look for injection vulnerabilities when reviewing source code and prevent them by properly validating and sanitizing all user input before adding it to applications. 

Use static code analysis

Static analysis security testing (SAST) is a type of static code analysis designed to detect security vulnerabilities. In contrast to other kinds of security testing (e.g., penetration testing and dynamic application security testing), SAST does not require the application to be executed. This means it can be performed earlier in the software development process, before application deployment.

SAST involves the following steps:

• Code scanning: SAST tools scan the code for coding errors, coding standards violations, security vulnerabilities, and other quality issues.

• Issue identification: The tool then identifies potential issues and presents them in the form of a report or dashboard.

• Prioritization: Sometimes, the tool will prioritize the issues based on their severity or impact on the application.

• Remediation: Finally, the developer can take action to remediate the identified issues.

The benefits of developer-first SAST tools 

SAST tools analyze the source code of an application for potential security vulnerabilities. Developer-first SAST tools are designed with the developers in mind and aim to optimize their workflow. Benefits of developer-first SAST tools include 

• Early detection of security vulnerabilities: By detecting security vulnerabilities early in the software development lifecycle, SAST tools make it easier and less expensive.

• Ease of integration: Developer-first SAST tools are designed for seamless integration so developers can easily apply them to their workflow.

• Faster development cycles: SAST tools enable developers to deliver software faster and with fewer defects.

• Reduced cost: SAST tools can help reduce the cost associated with late defect detection.

• Improved code quality: SAST tools improve code quality by pinpointing issues that could result in security vulnerabilities or other defects.

DevSecOps & Snyk: Dev tools so you can build securely from the start

Development practices have fundamentally changed, and so should your approach to security. New methods and challenges make the traditional, slow, siloed approach impossible to sustain as both code and threats scale. A better strategy involves leveraging platforms and tools that seamlessly work together so you can swiftly and reliably spot any vulnerabilities that may compromise the security of your software applications. And Snyk has just the products that combine to form a unified, holistic solution. 

Snyk Open Source

With Snyk Open Source, you can detect and resolve security vulnerabilities in the open source libraries employed by your applications. Additionally, it enables you to detect and resolve licensing problems related to these libraries or caused by them. Snyk Open Source supports multiple popular languages and platforms.

Snyk Code

A code checker powered by AI, which examines your code for potential security problems and offers actionable recommendations straight from your IDE to facilitate prompt resolution of vulnerabilities.

Snyk Container

Container and Kubernetes security help developers and DevOps quickly discover and remediate vulnerabilities throughout the SDLC. With Snyk Container, you can create images with security built-in from the start. 

Snyk IaC

Snyk IaC automates the security and compliance of your Infrastructure as Code (IaC) in development workflows pre-deployment and identifies missing or drifted resources after post-deployment, all to help you minimize risk.

Create a Snyk account to find and fix vulnerabilities in your code, dependencies, containers, and cloud infrastructure, such as SQL injections.