While end-users will see the versatile features that come from an application as appealing, developers, developers will find value in the robust code behind them. However, due to intense code sharing and feature-driven development, there has been an increase in potential security threats. In fact, studies have estimated that 92% of web applications have exposed security flaws and weaknesses that could easily be exploited by an intruder with rudimentary skills.
That’s why it’s more important than ever to perform secure code reviews on a regular basis.
The fact is, standard security testing isn’t enough. Most IT teams incorrectly believe that if you integrate security testing in the software development life cycle, it’ll be sufficient to prevent errors or threats. Many security exploits can go unnoticed by security testing applications, which can create high risks at a later stage of deployment. But, if you make secure code reviews a regular part of the development process, potential threats that would go unidentified by standard testing tools can be identified earlier and addressed.
What is a secure code review?
Technically, a secure code review is a strategic process to audit the source code to identify vulnerabilities or errors in the software. It’s used to verify that proper security controls are implemented throughout the system.
One of the major concerns associated with planning a secure code review is the selection of the right tools, processes and personnel that align with your organizational needs. Enterprises will often contemplate the idea of a secure code review and which tool or process is the right one to use.
Broadly, there are two types of secure code review: manual and automated. Here are some pros and cons of each to give you a clear understanding of how they perform individually.
The benefits of a manual secure code review include:
- Expert professionals can dive deep into code and identify vulnerabilities that could compromise the application; and
- It helps to identify logical flaws or errors, especially in the design and architecture of an application.
Some of the drawbacks to the manual secure code review process include:
- A manual secure code review is a time-consuming process;
- It calls for experts who are highly knowledgeable in both the security and development aspects of a software; and
- Different reviews can often lead to inconsistent reports, which can disrupt the proper flow of the software development lifecycle.
In contrast, the benefits of an automated review include:
- It can test large chunks of code in a short period of time, which plays a crucial role in continuous integration environments and agile methods like Scrum;
- High uptime and on-demand services;
- It is an efficient way to detect security issues such as data validation, authentication and authorization; and
- Customized automated tools to align with your organizational needs.
Drawbacks to the automated secure code review include:
- Tools with limited customization can result in difficulties with code review;
- Contain high numbers of false positives (items listed as issues but aren’t);
- Often show false negatives (issues that exist but aren’t detected);
- High licensing costs often eliminate it as a viable option for many small and medium-scale enterprises; and
- Requires personnel skilled in security, development AND operating the tool
Problems a secure code review solves
A secure code review reveals flaws or potential vulnerabilities in software that aren’t otherwise apparent. These could be implementation issues, design flaws, data validation errors, configuration issues or many other problems.
It also helps to identify weak security controls that might take long periods of tedious testing to find via dynamic testing. For instance, if an application uses blacklists to prevent an SQL Injection, this can be readily identified in a code review. However, it may take a long time to identify the same issue via dynamic testing, depending on how good the blacklist is. Other examples include cryptography issues, improper data storage, password validation and more.
Organizations that incorporate secure code reviews into their development process can see benefits such as:
- Provides consistent issue documentation;
- Helps deliver safe code;
- Reduces cost and time invested in identifying, fixing and debugging vulnerabilities;
- Promotes knowledge sharing between developers;
- Helps in the early detection of potential vulnerabilities in the design phase;
- Can cross-check the entire code with business logic and data validation to give a complete review; and
- It ensures that the software complies with your enterprise coding standards.
Secure code review best practices
Here are some of the best practices to follow while you implement secure code reviews:
- Create a code review checklist
Each application could contain hundreds of thousands of code lines. If different reviewers work together, you must ensure that they follow a single, comprehensive methodology. A checklist can help keep track of that.
As the secure code review process progresses, some of the reviewers might discover errors that are outside the radar of your checklist. Make sure that you encourage all reviewers to update the checklist whenever it’s required. Also, maintain a timeline for the review process. It can be a helpful tool to motivate reviewers to finish the task in a given timeframe.
- Categorize vulnerabilities according to risk
Software vulnerabilities may include buffer overflows, SQL Injection, OS command injection or any myriad of other security vulnerabilities. It’s essential to categorize threats to maintain a smooth flow and address dangerous threats first.
Bugs in data validation can also be reduced or eliminated if you customize automated review tools to your needs.
- Use a combination of manual and automated approaches
Automation technology — though highly advanced — doesn’t possess the power of the human brain yet. It can’t easily detect logical or reasoning errors in code, which can later put the entire application at risk.
Similarly, even the most knowledgeable and highly-trained professionals can miss some flaws of the code during the review process.
Thus, the ideal combination is a blend of both manual review and customized automatic static analysis testing. Manual code review can be implemented to verify the business logic of the code and to ensure compliance. Automated secure code review can be used to verify common vulnerabilities such as Cross-Site Scripting, SQL Injection, etc.
- Continuous monitoring and debugging
Some organizations review the entire application at once, right before release. The best time to implement a secure code review plan is at the beginning of the software development life cycle. You can integrate secure code review tools in your CI/CD pipeline, which will lead to the early detection of issues or possible threats.
Also, whenever a developer modifies the code, the automated security tools will run a scan of the updated code. If you regularly follow this practice, you can reduce security issues and ensure that your code compiles with your business goals as it progresses with time.
Why a secure code review is important
When your development team fixes issues in the early stages of the software development lifecycle, it provides additional benefits to developers and the organization. For example, you can encounter fewer problems at the release stage and don’t have to worry about unknown risks caused by code vulnerabilities.
A proper secure code review helps identify issues in application code. There are plenty of secure code review tools on the market. While some work specifically for a specific programming language, others can understand several frameworks, languages and platforms.