Security Code Review Explained: From Basics to Best Practices [2025]

The 2023 SolarWinds attack hit over 30,000 organizations. That’s not a typo.

Hackers slipped into systems of 18,000+ customers—all through a poisoned software update. It wasn’t some brute-force hack. It was a surgical, supply chain takedown. And it worked because security gaps quietly slipped through review.

Here’s the kicker: this could’ve been caught with better code review.
Secure code review is no longer a nice-to-have. It’s mission-critical. Especially when 78% of enterprise software is open source—and 87% of it carries built-in risks. Even AI isn’t helping much. A recent study found that 62% of AI-generated code contains security flaws.

Companies know the stakes. Application security spending jumped from $4.9 billion in 2021 to $7.5 billion in 2023. But throwing money at tools doesn’t help if you’re not reviewing what’s being shipped.

The breaches keep coming. And they’re getting smarter.

SolarWinds wasn’t just a wake-up call. It was proof: when code review fails, attackers walk right in, impersonate users, and move laterally across your network like it’s a hotel lobby.

Let’s unpack what secure code review really means—and how to do it right.

What Is Secure Code Review?

Secure code review is the practice of digging through your code—line by line—to catch security flaws before attackers do.

It’s not your typical code review. This isn’t about formatting, style, or logic bugs. It’s about spotting the real threats: SQL injection points, broken authentication flows, insecure API changes, misconfigured access controls, bad OAuth setups—you get the idea.

Done right, it’s a mix of humans and machines. Automated tools help you scale. Manual inspection brings the context. You need both.

Here’s how it works:

• Focus on risk—not just code cleanliness.
• Review early and often—before anything hits production.
• Don’t just scan—understand how components interact in the real world.

Why it matters:

• You catch vulnerabilities when they’re cheapest to fix.
• Your developers level up in secure coding with every review.
• You reduce the number of security bugs that ever reach production.

If you’re pushing code without reviewing it for security, you’re not just moving fast—you’re flying blind.

Secure Code Review Process: How to Do It Right

Running a secure code review isn’t just about checking boxes—it’s about building security into your dev pipeline. Here’s what a solid review process looks like, step by step:

1. Define the Scope
2. Set Security Baselines
3. Run Automated Scans First
4. Follow Up With Manual Review
5. Document and Triage Findings
6. Fix, Re-Test, and Validate
7. Build It Into CI/CD
8. Learn and Level Up

Secure Code Review Process

Let’s break each one down—so you know what to prioritize and when.

1. Define the Scope

• Know what you’re reviewing—new features, sensitive modules, or the whole repo.
• Prioritize high-risk areas like auth flows, data handling, and external integrations.

2. Set Security Baselines

• Use a threat model or secure coding checklist (like OWASP Top 10) as a reference.
• Make sure everyone agrees on what “secure” means before diving in.

3. Run Automated Scans First

• Use SAST, SCA, or linting tools to catch common flaws quickly.
• Flag low-hanging fruit like hardcoded secrets, SQL injection, and outdated dependencies.

4. Follow Up With Manual Review

• Focus on logic flaws, access controls, and design-level issues automation can’t catch.
• Review the code in context—look at how different components interact.

5. Document and Triage Findings

• Log every issue with context, severity, and fix recommendations.
• Distinguish between critical blockers and nice-to-haves.

6. Fix, Retest, and Validate

• Developers fix the bugs.
• Security re-tests critical fixes.
• Validate that new code doesn’t introduce new risks.

7. Build It Into CI/CD

• Automate what you can.
• Gate pull requests on passing scans and review approvals.
• Make security checks part of the workflow—not an afterthought.

8. Learn and Level Up

• Review outcomes with your dev team.
• Share common mistakes and prevention tips.
• Turn each review into a chance to upskill your developers.

Manual, Automated, or Both?

Once you’ve nailed down the review steps, the next question is how to execute them—manually, automatically, or both? Each method brings its own strengths and trade-offs. Here’s how they compare:

The table makes it clear: no single method wins across the board. Manual reviews catch complex logic issues, automation excels at speed and scale—but only a hybrid approach delivers both depth and efficiency. That’s why teams aiming for real security rely on a balanced, combined strategy.

Importance of Secure Code Review

Vulnerabilities aren’t just a dev concern—they’re a business liability. Fixing flaws early can save millions, especially in high-impact industries like healthcare and transportation.

Here’s why secure code review is worth the investment:

• Lower Remediation Costs
  Fixing bugs in development is up to 10x cheaper than patching them post-release.
  It also saves developer hours that would otherwise go into firefighting post-deployment.

• Reduced Breach Risk
  Early detection prevents vulnerabilities from escalating into security incidents that damage trust and revenue. Every issue caught in code review is one less entry point for attackers.

• Improved Code Quality
  Systematic reviews lead to fewer bugs in production and more resilient software overall.
  Security issues often overlap with architectural and logic flaws—catching both improves maintainability.

• Security-First Culture
  Regular reviews help devs think like attackers—and code defensively by default.
  That mindset shift leads to cleaner, more intentional code across the board.

• Streamlined Compliance
  Helps teams meet regulatory requirements like GDPR, HIPAA, and ISO 27001 with less friction. Auditors love documented reviews—they prove due diligence and reduce compliance headaches.

• Smarter, Faster Workflows
  Tools like SAST, OWASP checklists, and secure SDLC practices speed up detection without slowing delivery. Security becomes part of the pipeline—not a blocker slapped on at the end.

Bottom line: secure code review pays off—in cost savings, compliance, and peace of mind.

Secure Code Review Tools

Effective secure code review requires specialized tools that complement human expertise. Modern security demands multiple detection methods to catch vulnerabilities across different development stages.

These are the core types of security testing tools used during secure code review:

1. Static Application Security Testing (SAST)
2. Dynamic Application Security Testing (DAST)
3. Interactive Application Security Testing (IAST)
4. Software Composition Analysis (SCA)

Secure Code Review Tools

Let’s break down what each one does—and where it fits in your security workflow.

1. Static Application Security Testing (SAST)

SAST tools examine source code without executing it, identifying vulnerabilities during development. These tools scan for issues like SQL injection, buffer overflows, and authentication weaknesses. They identify vulnerabilities before code execution, enabling faster remediation.

SAST integration with IDEs and CI/CD pipelines creates seamless workflow incorporation. However, these tools generate false positives and struggle with complex modern frameworks. Organizations frequently incorporate SAST as part of comprehensive OWASP-aligned strategies.

2. Dynamic Application Security Testing (DAST)

DAST tools test running applications from external perspectives, simulating actual attack scenarios. They identify vulnerabilities in production-like environments without requiring source code access—particularly valuable for testing third-party applications. DAST tools also support regulatory compliance requirements like PCI.

Forrester estimates DAST scans take approximately 5-7 days to complete, representing the primary limitation of this approach.

3. Interactive Testing (IAST)

IAST bridges static and dynamic testing by monitoring applications during runtime. Developers prefer IAST for several reasons: it provides real-time vulnerability detection with minimal false positives, offers context-aware reporting for faster remediation, and works at "pipeline native speeds" without slowing development.

Leading IAST solutions include Contrast CE, Checkmarx IAST, and HCL AppScan.

4. Software Composition Analysis (SCA)

The average application uses 147 different open source components, making SCA tools essential for modern development. SCA tools provide comprehensive inventory of all open source components, identify known vulnerabilities in dependencies, monitor license compliance for legal risk management, and generate software bill of materials (SBOM).

Organizations now establish dedicated testing environments and training programs to evaluate tool effectiveness across real-world scenarios. The combination of these four tool categories—SAST, DAST, IAST, and SCA—creates layered security coverage that addresses vulnerabilities at multiple development phases.

Creating a Secure Code Review Checklist for Your Team

Security checklists are now a must-have for dev teams. The 2024 OWASP Top 10 found that 62% of breaches stem from code-level flaws—most of which proper review could have caught. Structured checklists ensure teams consistently cover the most critical security risks.

These are the checklist areas every secure code review should cover:

1. Input Validation and Output Encoding
2. Authentication and Session Management
3. Access Control and Authorization
4. Error Handling and Logging
5. Third-Party Dependencies

Secure Code Review Checklist

Let’s break down what to check in each area.

1. Input Validation and Output Encoding

• Validate all untrusted inputs—including from databases and file streams.
• Use allow lists instead of deny lists.
• Apply context-aware output encoding to all client-facing data.
• Specify character sets like UTF-8 to avoid encoding-related bugs.

2. Authentication and Session Management

• Session IDs need at least 64 bits of entropy.
• Set cookies with HttpOnly and Secure flags.
• Invalidate session tokens on logout.
• Use generic error messages—never reveal which credential failed.

3. Access Control and Authorization

• Enforce auth checks on every request, including server-side.
• Apply least privilege principles.
• Implement and validate role-based access controls (RBAC) consistently.

4. Error Handling and Logging

• Avoid exposing stack traces or system info in error messages.
• Log security events like failed logins and access violations.
• Never log sensitive data (e.g., passwords, credit cards, PII).

5. Third-Party Dependencies

• Vet all libraries for reputation and maintenance status.
• Use tools like OWASP Dependency-Check or Snyk.
• Lock versions in configs—avoid unexpected updates.
• Review changelogs for potential security changes.

Modern teams embed these checks into CI/CD pipelines, backed by practical training and secure coding labs. The result? Cleaner code, fewer breaches, and stronger compliance.

Secure Code Review Courses and Labs

Security skills now directly impact career growth for developers. As threats grow and compliance tightens, teams are turning to specialized training to catch vulnerabilities before code hits production.

Stanford University teaches developers to identify flaws using static/dynamic analysis and defend against control hijacking, supported by a hands-on ethical hacking lab.
SEI CERT’s certificate delivers 20+ hours of training on string management, integer overflows, and race conditions—with 12-month access for working professionals.

Several platforms offer practical, lab-based security training:

• Secure Code Warrior: 500+ hours of content across 225+ topics in 65+ languages
• SecureFlag: Thousands of labs on 150+ vulnerabilities across 45+ tech stacks
• Veracode Security Labs: Live environments for web and mobile code review
• MCSI: OWASP-aligned training with threat modeling and secure SDLC practices

The demand is rising. Readynez offers unlimited access to 60+ instructor-led courses—mirroring the industry’s hunger for security talent.

Comprehensive programs blend theory with hands-on learning, covering:

• Vulnerability detection and automation
• Secure coding checklists and planning
• Compliance requirements for SOC 2, HITRUST, and PCI

For dev teams today, secure code training isn’t optional—it’s essential.

Secure Code Review OWASP Best Practices

The Open Web Application Security Project (OWASP) sets the standard for secure code review. Teams that align with OWASP practices reduce vulnerabilities by up to 36% during development—before issues ever reach production.

Core resources to follow:

• OWASP Code Review Guide – Covers how to identify and fix code-level vulnerabilities
• OWASP Top 10 – Highlights the most common and dangerous web application flaws
• CWE Top 25 – Lists the most critical software weaknesses across platforms
• CERT Coding Standards – Offers language-specific secure coding best practices

Developers should take ownership of these guidelines, supported by the security team. Keeping them updated is essential as frameworks and threats evolve.

Training Developers for Real-World Security

Strong training isn’t a one-off event. The most effective programs mix:

• Structured workshops on secure coding
• Self-paced learning and internal knowledge-sharing
• Hands-on review labs with real code and real flaws

This blended approach builds awareness, skills, and long-term secure coding habits.

Embedding Reviews into Agile & DevSecOps

Security needs to move at dev speed:

• Use IDE-integrated SAST tools to catch issues early
• Review code incrementally, not just at release
• Track security bugs in the same backlog as feature work

This integration reduces rework and flags issues before they escalate.

Metrics That Matter

MTTR (Mean Time to Remediate):
This measures how long it takes to fix a vulnerability after discovery. The industry average is 57.5 days—plenty of time for attackers to take advantage. Teams using contextual micro-learning and real-time feedback have slashed MTTR by up to 92%, cutting exposure dramatically.

Defect Density:
This tracks bugs per 1,000 lines of code (KLOC) to measure code quality. But context matters. A 0.6/KLOC rate might be fine for a complex scheduling engine, while 0.4/KLOC in a basic CRUD app could signal deeper problems. Always consider complexity and risk.

Making Secure Code Review a Continuous Practice

Organizations are ditching periodic security checks in favor of continuous code review—and for good reason. Teams that embed security feedback directly into development cycles fix vulnerabilities 92% faster than those relying on traditional reviews.

This shift isn’t just technical—it’s cultural. Today, over 60% of developers build code review into their daily routine or block out time for it. That change is driving real results.

Here’s how modern teams make it work:

• SAST and SCA tools scan automatically in CI/CD
• IDE plugins flag risks as code is written
• Defect density tracks security improvement over time
• Review checklists evolve with emerging threats

ASPM tools provide ongoing visibility, while manual reviews catch the high-risk issues automation misses. This creates a “continuous feedback loop” that strengthens secure coding habits and accelerates DevSecOps maturity.

Quality gates prevent risky code from merging. Documentation closes the loop, helping teams learn from the past—and ship better code in the future.

Bottom line? Secure code review isn’t just a task. It’s a habit, a mindset, and the foundation for building software that’s actually safe.