How we manage vulnerabilities at Paystack

As more businesses go digital and online threats grow more sophisticated, cybersecurity has become critical to business success. Companies that rely on code must stay ahead of vulnerabilities to protect their systems, data, and customers.

For African businesses embracing digital payments, the risks are even higher. A single security failure can lead to financial loss, data breaches, or lasting reputational harm.

At Paystack, over 200,000 African businesses trust us to power secure, reliable payments. This responsibility drives us to take a proactive approach to security, embedding protections directly into how we build. We call this “shift-left” security—integrating security checks from the very start, so vulnerabilities are caught and fixed early.

One key part of this approach is Static Application Security Testing (SAST). In this article, we’ll show you how we use SAST at Paystack, why it matters, and how it fits into our broader vulnerability management process.

Whether you’re an engineer curious about our workflow or a startup exploring ways to strengthen your security practices, we hope you find this insightful.

Core principles of vulnerability management

At its core, vulnerability management is about staying one step ahead of attackers. It’s the ongoing practice of identifying, assessing, prioritizing, and fixing security weaknesses before they can be exploited.

Every system, app, or network can have vulnerabilities, gaps that might allow unauthorized access, data leaks, or disruptions. And the longer a vulnerability stays unfixed, the greater the risk.

That’s why engineers follow a structured process at every stage of development:

• Detection: Finding potential vulnerabilities in code or systems
• Evaluation: Assessing how severe each issue is and its potential impact
• Planning: Prioritizing which issues to tackle first based on risk
• Remediation: Fixing the issues to remove the threat
• Verification and reporting: Double-checking that fixes work and tracking what’s been addressed

This proactive approach to vulnerability management is essential for maintaining secure and resilient systems.

Using Static Application Security Testing (SAST) for vulnerability management

To put our shift-left security principles into action, we’ve integrated Static Application Security Testing (SAST) into our Software Development Lifecycle (SDLC). SAST is an automated process that helps developers catch vulnerabilities in the source code before they can be exploited, ensuring our software is secure from the start.

Traditionally, managing vulnerabilities was a manual process. Security teams had to review code by hand, use basic scanners, and track vulnerabilities in spreadsheets or simple tools. While these methods laid the groundwork for modern practices, they were slow, error-prone, and difficult to scale as projects grew.

Automating the detection stage of vulnerability management with SAST has been a game changer. At Paystack, SAST allows us to continuously scan source code for security issues in real time. Unlike manual reviews, which can miss certain problems, SAST tools can scan the entire codebase and identify potential security flaws that might be overlooked by human reviewers.

Implementing SAST at Paystack

We’ve designed our SAST workflow at Paystack to integrate into our existing Software Development Lifecycle (SDLC). This approach allows us to identify vulnerabilities without compromising the speed or agility of software development.

Setting up scanning across all repositories: The first step in our SAST workflow is configuring SAST tools across all our GitHub repositories. These tools automatically scan for vulnerabilities whenever code is committed or a pull request (PR) is created, ensuring security is built into the development process from the start.

• CodeQL: CodeQL is used for deep semantic code analysis. Unlike traditional SAST tools that rely on simple pattern matching, CodeQL uses a query language to detect complex vulnerabilities in the code. This helps us identify security flaws that might otherwise go unnoticed.
• Dependabot: Dependabot manages third-party dependencies, scanning them continuously for known vulnerabilities. When a vulnerability is found, Dependabot automatically opens a PR with the necessary updates, ensuring we’re always using the most secure versions of libraries.
• Secret Scanning: Hardcoded credentials like API keys and passwords pose a significant security risk. Our secret scanning tools are configured to automatically detect and block these sensitive details in our repositories. We’ve customized the tools with specific patterns (using custom regular expressions) to fit our environment.

Editors note: CodeQL and Secret Scanning require a GitHub Advanced Security (GHAS) license to run on private repositories, outside of GitHub.com’s public repositories.

Continuous integration and automated scanning: Our SAST tools are fully integrated into our Continuous Integration/Continuous Deployment (CI/CD) pipelines. This means every time a developer commits code or submits a PR, the SAST tools automatically scan the code for vulnerabilities. If any issues are detected, the tools flag them immediately, blocking the PR until the vulnerabilities are addressed.

Triage and prioritization: When a vulnerability is detected, it goes through our triage process, where it’s evaluated based on severity, exploitability, and potential impact. High-severity vulnerabilities—especially those that could lead to data breaches or unauthorized access—are prioritized for immediate remediation. Medium- and low-severity vulnerabilities are scheduled for remediation based on their risk level and available resources.

Enforcement of security policies: To ensure vulnerabilities are not ignored or bypassed, we’ve implemented strict security policies in our GitHub environment. For instance, our GitHub Actions are configured to block the merging of PRs with unresolved vulnerabilities. This guarantees that only secure code makes it into the main branch, reducing the risk of introducing vulnerabilities into production.

Remediation and continuous improvement: Remediation isn’t the final step in our SAST workflow. We continuously review and refine our processes to strengthen our security posture. After vulnerabilities are resolved, we conduct post-remediation reviews to identify gaps and prevent similar issues in the future. This ongoing improvement ensures our security practices evolve alongside our development processes.

Key metrics for continuous improvement in vulnerability management

We’re big on continuous improvement even after vulnerabilities have been remediated. Every time we go through the lifecycle of a vulnerability—from detection to remediation—we learn something new that helps refine our workflow.

Here are the key metrics we use to track how well our SAST workflow is working:

Mean Time to Detection (MTTD): MTTD measures the average time it takes to detect a vulnerability after it’s introduced into the code. A shorter MTTD indicates that our SAST tools are effective at quickly identifying vulnerabilities, allowing us to address them before they pose a threat. Reducing MTTD is critical for minimizing the window of exposure and ensuring timely remediation.

Mean Time to Remediation (MTTR): MTTR tracks how long it takes to fix a vulnerability once it’s detected. A lower MTTR suggests that our remediation processes are efficient, allowing us to respond quickly and reduce the risk of exploitation. This metric helps us assess how well we manage and prioritize fixes, ensuring vulnerabilities are patched promptly.

Vulnerability introduction rate: This metric monitors the rate at which new vulnerabilities are introduced into our codebase. By tracking trends, we can identify areas where improvements are needed—such as if a particular team or project consistently introduces more vulnerabilities. This insight helps guide targeted security training or process adjustments to improve code quality and reduce risks.

Enablement rates: Enablement rates measure the percentage of our repositories covered by SAST tools and the variety of programming languages and frameworks supported. High enablement rates ensure we maintain comprehensive coverage, reducing the chances of vulnerabilities slipping through undetected.

Challenges and limitations of using SAST

While we continuously monitor and improve vulnerability management at Paystack, SAST tools do have their limitations. They aren’t foolproof, and using them can bring challenges that affect both accuracy and efficiency.

We’ve encountered some of these issues and have taken steps to address them, but it’s important to recognize the challenges that come with automated vulnerability management:

False positives: Automated SAST tools can sometimes flag false positives, alerts for issues that aren’t real vulnerabilities. This can lead to “alert fatigue,” where developers may start ignoring alerts, potentially missing actual security threats. Our security engineering team mitigates this by fine-tuning the SAST tools and implementing a triage process to verify the validity of each alert.

Language and framework coverage: Comprehensive coverage across all programming languages and frameworks is essential. Some SAST tools perform well in one language but poorly in others. To address this, we use a combination of SAST tools tailored to our specific technology stack, ensuring that all parts of our codebase are properly checked.

Integration with existing workflows: Integrating SAST tools into development workflows without slowing down productivity can be challenging. At Paystack, we’ve successfully integrated SAST tools into our GitHub repositories and CI/CD pipelines, ensuring that security checks run seamlessly as part of the development process.

The future of vulnerability management at Paystack

We recognize that no system is without its challenges, and automated tools aren’t perfect. But by continuously refining our processes, addressing limitations, and learning from every vulnerability we encounter, we’re strengthening our security posture and enhancing our ability to prevent and respond to emerging threats.

Looking ahead, we’re exploring new approaches to detect and mitigate esoteric logic vulnerabilities, those subtle, context-specific flaws that can evade traditional scanning tools. We’re also developing advanced fuzzing strategies tailored to our infrastructure, designed to uncover hidden vulnerabilities and edge cases.

These efforts are part of our long-term roadmap for vulnerability management: an ongoing investment in building secure, resilient systems that protect the businesses we’re privileged to serve.

And as we continue evolving our security practices, we remain focused on staying ahead of emerging threats while embedding security seamlessly into every stage of the development process.

If you’d like to learn more about how Paystack protects your business, or have questions about strengthening your security practices, reach out to us anytime at [email protected] 💙