10 Secure Code Review Best Practices for Developers

Want to catch security issues before they become problems? Here's how to do secure code reviews right:

1. Set clear goals

2. Use security tools

3. Perform manual checks

4. Check input handling

5. Verify user access controls

6. Review data security

7. Check error handling

8. Examine external libraries

9. Limit access rights

10. Keep learning

Quick Comparison:

Practice	Key Benefit	Challenge
Set goals	Focuses review	Time-consuming
Use tools	Finds common issues	Can miss context
Manual checks	Catches subtle flaws	Labor-intensive
Input handling	Prevents attacks	Needs constant updating
Access controls	Limits damage	Complex to manage
Data security	Protects sensitive info	Requires ongoing effort
Error handling	Avoids info leaks	Balancing user/dev needs
Library checks	Reduces vulnerabilities	Time-consuming
Access limits	Minimizes attack surface	Can hinder workflow
Continuous learning	Stays ahead of threats	Requires dedication

Secure code review isn't just box-ticking. It's about building a security-first mindset. Start early, use tools and your brain, and never stop learning. Your code (and users) will thank you.

Related video from YouTube

1. Set Clear Goals

Setting clear goals is key to an effective secure code review. It helps you focus on what matters most and makes your review more efficient.

Here's how to do it:

1. Pick your targets: Focus on the riskiest parts of your code. Think authentication, data handling, and sensitive info areas.

2. List vulnerabilities: What security issues do you want to catch? SQL injection? XSS? Buffer overflows? Write them down.

3. Set your standards: Create clear security guidelines based on your company's rules and industry best practices. Make sure everyone can access them easily.

4. Make a checklist: Build a thorough list of security aspects to review. It'll keep your reviews consistent and thorough.

5. Define your scope: Decide which parts of the code you'll review and how deep you'll go. This helps manage your time and resources.

Here's a real-world example:

"At Snyk, we set clear objectives for each code review. This cut post-deployment security issues by 40% and sped up our development cycle by 25%", says Guy Podjarny, Snyk's Founder.

2. Use Security Tools

Security scanning tools are crucial for catching vulnerabilities in your code. They spot issues that humans might miss, saving time and boosting security.

Here are some top tools:

• Veracode: Scans pipelines, policies, and IDEs. Ranks vulnerabilities by severity.

• Snyk: Does software composition analysis and static application security testing. Reviews code and ranks risks.

• Kiuwan Code Security: SAST solution that scans source code early. Uses 4000+ rules based on 25 security standards.

To maximize these tools:

1. Integrate with your workflow

Set them up to run automatically in your CI/CD pipeline.

2. Focus on high-risk areas

Pay extra attention to code handling sensitive data or user input.

3. Keep tools updated

Security threats change. Make sure your tools have the latest rules.

4. Don't rely solely on tools

Use them alongside manual reviews, not instead of them.

Here's a quick comparison:

Tool	Best For	Key Feature	Integration
Veracode	Enterprise-level security	Comprehensive scanning	CI/CD pipelines
Snyk	Real-time vulnerability detection	DeepCode AI for quick fixes	IDEs, Git
Kiuwan	Early vulnerability detection	4000+ security rules	Major IDEs

Remember: Tools are great, but they're not perfect. Always use your brain too!

3. Perform Manual Checks

Automated tools are great, but they're not perfect. You need manual code reviews to catch the tricky stuff machines miss.

Here's how to do it right:

1. Hit the hot spots: Focus on authentication, data handling, and user input. That's where the bad guys love to poke around.

2. Use a cheat sheet: Make a list of common vulnerabilities. It'll keep you on track.

3. Go line by line: Slow down and really look at each line. How could someone mess with it?

4. Think like a hacker: Try to break your own code. Where are the weak spots?

5. Hunt for secrets: No passwords or API keys in plain sight, right?

6. Check error handling: Make sure errors don't spill the beans about your system.

7. Lock it down: Double-check those user permissions. Are they airtight?

8. Look at the big picture: How does your code play with databases and other services?

"Code reviews aren't just about the code. If you're looking at an API, there's probably a reverse proxy in front of it. You've got to think about the whole environment." - Vitor Costa, Senior Customer Support, Hack The Box

Manual reviews take time, but they're worth it. You'll catch sneaky bugs and level up your security game.

Manual Review	Automated Tools
Catches subtle flaws	Finds common issues fast
Considers context	Consistent results
Improves team skills	Handles big codebases
Finds logic errors	Works with CI/CD

4. Check Input Handling

Input handling is your first defense against many attacks. Here's how to do it right:

1. Check inputs ASAP

2. Define what's allowed, not what's banned

3. Ensure inputs are formatted correctly and make sense

4. Clean up data before using it

5. Use built-in framework functions for input handling

Quick comparison:

Method	Pros	Cons
Allowlisting	Very secure, clear rules	Can be restrictive
Denylisting	Flexible, easy to implement	Can miss new attack vectors
Sanitization	Preserves most input data	May alter user intent
Encoding	Preserves all input data	Doesn't prevent all attacks

Don't forget: Check ALL external data, including API calls, file uploads, database queries, and command-line arguments.

"Input validation can significantly reduce the impact of XSS, SQL Injection, and other attacks when implemented correctly." - OWASP Foundation

Always validate on the server side. Attackers can bypass client-side checks.

Finally, try to break your input handling with unexpected inputs. Find the holes before the bad guys do.

5. Verify User Access Controls

User access controls keep your code secure. They ensure only the right people can access specific parts of your system.

Here's how to check user access controls during code review:

1. Look for role-based access control (RBAC)

RBAC links user permissions to job roles. It's simpler and safer.

Example: In a company app:

• Sales team sees customer data

• HR accesses employee records

• IT admins have full system access

2. Check for least privilege

Users should only have the minimum access needed for their job. This limits potential damage from compromised accounts.

3. Verify strong authentication

Look for multi-factor authentication (MFA) in the code. It adds security beyond passwords.

4. Review session management

Ensure the code handles user sessions safely:

• Set secure session timeouts

• Use strong session IDs

• Invalidate sessions on logout

5. Audit access regularly

The code should allow for regular access reviews. This catches outdated or incorrect permissions.

Access Review Step	Purpose
Check inactive users	Remove unnecessary access
Review role assignments	Ensure correct permissions
Look for privilege creep	Prevent excess access over time
Verify third-party access	Manage external partner risks

Good access controls are crucial for meeting security standards like SOC 2 and ISO 27001.

6. Review Data Security

Data security is crucial in secure code review. Here's what to check:

1. Encrypt sensitive data

Use strong encryption for data at rest and in transit:

• At rest: AES-256 for credit card numbers

• In transit: TLS 1.3 for API calls

2. Hash passwords

Never store plain text passwords. Instead:

• Use Argon2id or bcrypt

• Add a unique salt to each password

3. Limit data access

Follow the principle of least privilege:

• Give users access to only what they need

• Audit and update access rights regularly

4. Secure key management

Protect encryption keys:

• Store keys separately from encrypted data

• Use a hardware security module (HSM)

5. Check for data leaks

Look for accidental data exposure:

• Review logs for sensitive info

• Check error messages for data leaks

Data Type	Protection Method
Passwords	Hashing (bcrypt)
Credit Cards	Encryption (AES-256)
Personal Info	Access Controls
API Keys	Secure Key Management

Remember: Data security isn't just about encryption. It's about creating layers of protection to keep sensitive information safe.

7. Check Error Handling

Good error handling is crucial for secure code. Here's how to do it right:

1. Keep it vague for users

Don't give away the farm. Use simple messages like:

"Oops! Something went wrong. Try again?"

This keeps attackers in the dark about your system.

2. Log the details

Save the juicy stuff for your server logs. It helps with fixing issues without risking exposure.

User sees	Server log has
"Error. Try again."	Full error trace, code, context
"Invalid input."	Exact validation fail details

3. One error handler to rule them all

Set up a central error manager. It keeps things consistent.

In Java web apps? Use web.xml. Spring Boot fan? Try @RestControllerAdvice.

4. Hunt for leaks

Double-check your error code. Make sure it's not spilling secrets like:

• Database info

• File locations

• Software versions

5. Break it to make it

Don't just test the happy path. Try to crash your code. It's better you find the bugs before the bad guys do.

"Error messages should be clear for users, but not a security risk. Help users understand what went wrong without exposing your system's guts." - Myat Su Phyo, Author

8. Examine External Libraries

Third-party libraries can speed up development, but they come with risks. Here's how to handle them:

1. Check the source

Download libraries only from official sites or trusted GitHub repos. This reduces fake package risks.

2. Scan for bugs

Use tools to find known issues:

Tool	Purpose
Snyk	Scans dependencies, fixes vulnerabilities
OWASP Dependency-Check	Identifies known issues in dependencies
Sonatype Nexus Lifecycle	Manages component quality and security

3. Keep a list

Track your external libraries. Include name, version, usage, vulnerabilities, and update schedule.

4. Update regularly

Set a schedule for library updates to stay protected against new threats.

5. Trim the fat

Remove unused libraries. Fewer dependencies = fewer potential issues.

6. Read the code

For critical libraries, review the source code to spot potential problems.

7. Watch for red flags

Be cautious of libraries with:

• No recent updates

• Few contributors

• Lack of documentation

8. Pin versions

Use specific version numbers to prevent unexpected changes.

Even trusted libraries can have issues. In 2021, Log4j, a popular logging library, had a major security flaw affecting millions of Java applications worldwide.

"Over 80% of codebases contained vulnerable open-source components in 2020. This shows how important it is to carefully manage third-party dependencies." - Synopsys Cybersecurity Research Center

Managing external libraries is a balancing act. They can save time, but they need careful handling to avoid introducing vulnerabilities into your project.

9. Limit Access Rights

Limiting access rights is crucial for secure code review. It's about giving users only what they need - nothing more.

Here's why it matters:

• 60% of attacks come from insiders (75% intentional)

• 27% of data breaches are caused by human error

To tackle this:

1. Apply the principle of least privilege (POLP)

Give users minimal access. It's safer if an account gets hacked.

2. Use role-based access control (RBAC)

Set permissions based on job roles. Makes managing access easier as people come and go.

3. Conduct regular access reviews

Check who has access to what. Remove unnecessary permissions.

4. Implement Just-In-Time (JIT) access

For high-access tasks, use JIT. It gives temporary elevated permissions that are logged.

5. Separate admin and standard accounts

Keep admin accounts separate. Adds an extra security layer.

Here's a quick implementation guide:

Step	How to Do It	Why It's Important
POLP	Audit permissions, remove excess	Smaller attack surface
RBAC	Define roles, assign permissions	Easier access management
Access Reviews	Quarterly reviews	Catches old permissions
JIT Access	Use tools like Azure AD PIM	Limits high-level access time
Account Separation	Create separate admin accounts	Prevents accidental misuse

Limiting access rights isn't a one-off task. It needs ongoing attention.

"The Principle of Least Privilege is foundational for effective application security and crucial for compliance standards like SOC 2 Type II, PCI-DSS, ISO 27001, and Fed RAMP." - National Cybersecurity and Communications Integration Center (NCCIC)

10. Keep Learning

In cybersecurity, staying updated is crucial for effective code review. New threats pop up daily, so continuous learning is a must.

Here's how to stay sharp:

1. Follow trusted sources: Subscribe to CISA's security bulletins and check CERT/CC and SecurityFocus for vulnerability alerts.

2. Use tech: Set up Google Alerts for security topics and follow security experts on Twitter.

3. Engage: Attend webinars, conferences, and join online discussions.

4. Read security blogs: Check out "Securing Tomorrow" by McAfee and "Dark Reading" for original research and news.

5. Watch IoT security: With the global IoT market set to double, stay informed about IoT-specific threats.

Make learning a habit. Set aside time each week to update your knowledge.

"Continuous education and awareness are critical components of maintaining this lead." - Cybersecurity and Infrastructure Security Agency (CISA)

The cybersecurity world doesn't stand still. Neither should you.

Conclusion

Secure code review isn't just about bug hunting. It's about baking security into your coding DNA.

Here's the deal:

• Start early. Security isn't a last-minute add-on.

• Tools are great, but your brain is better. Use both.

• See the forest AND the trees. How does everything fit together?

• Never stop learning. Threats evolve. So should you.

Code review isn't a box-ticking exercise. It's about creating a security-first mindset.

"I'm a big fan of code review, whether for identifying security bugs or 'regular' bugs." - Chris Bush, Author

Want to level up your code review game? Try this:

1. Schedule regular reviews

2. Use a security checklist

3. Mix up your review team

4. Track and learn from issues

Make these habits stick, and you'll catch problems early and build rock-solid software.

The cyber landscape is always shifting. But with these practices, you'll be ready for whatever comes next.

FAQs

What is the best practice of secure code review?

The best practice for secure code review? Robust authentication. It's all about treating every user as a stranger until they prove otherwise.

Why it's crucial:

• Stops unauthorized access

• Shields sensitive data

• Sets the stage for other security measures

Think of authentication as your security bouncer. Get it right, and you're already winning.

What is the most secure form of code testing and review?

Static Application Security Testing (SAST) tools take the crown here. They're like security guards for your code, scanning every line for potential threats.

SAST tools shine at:

• Spotting common coding slip-ups

• Finding vulnerabilities early

• Delivering consistent results

But here's the kicker: SAST tools aren't perfect. They're great at known issues but can miss context-specific problems. That's why pairing SAST with human reviews often works best.

Pro tip: Integrate SAST into your continuous integration pipeline. Catch issues before they even reach code review.