The OWASP Serverless Top-10

Understanding the OWASP Serverless Top 10

The Open Web Application Security Project (OWASP) unites a global community of application security experts, renowned for generating resources that provide a secure groundwork for modern applications. A widely recognized benchmark, the OWASP Top 10 outlines the most critical security vulnerabilities in web applications.

Within this article, we delve into the pinnacle of serverless vulnerabilities, shedding light on pivotal security considerations inherent to the deployment of serverless technology. This meticulous curation by OWASP empowers readers with profound insights into paramount security aspects, coupled with essential techniques to adeptly mitigate potential risks.

The Core of the Serverless Top Ten

Embracing serverless technology entails liberating applications and services from traditional server hosting. This approach capitalizes on the shared responsibility model, wherein cloud providers proactively address specific security threats. Furthermore, the serverless architecture optimizes costs by executing functions solely when needed, ensuring consistent performance through dynamic scaling.

However, the crux of the security challenge lies within the application code itself. If insecure code is deployed within a serverless environment, it can pose risks comparable to those in traditional servers or virtual machines. Application-level vulnerabilities endure. The OWASP Serverless Top Ten scrutinizes attack vectors, security vulnerabilities, business risks tied to successful serverless exploits, and the potential ramifications upon realizing these threats. This comprehensive analysis reveals mitigation strategies, encompassing both general best practices applicable to conventional assets and measures tailored to the nuances of serverless applications.

• Injection Vulnerabilities: In serverless applications, the injection attack surface expands, potentially escalating vulnerability severity. Unlike traditional scenarios, where API calls were the primary entry point, serverless functions can be triggered by diverse sources such as Emails, SMS, and IoT. Malicious scripts targeting this vulnerability can compromise code or expose secrets, potentially granting attackers permissions to cloud storage and other critical systems. Counteract this through input validation whitelisting, meticulous source validation, adherence to the principle of least privilege, and leveraging runtime defense solutions.

• Authentication Breakdown: The shift to serverless replaces a singular authentication flow with multiple, independent functions. Attackers may exploit public cloud storage, open APIs, and spoofed emails to trigger functions without proper authentication. Unauthorized access risks data leaks and service disruptions. Counteract this with robust cloud vendor-provided authentication solutions, utilization of federated services, encryption for secure channels, effective password and key management, and the implementation of certificates.

• Exposing Sensitive Data: Vulnerabilities such as compromised keys and man-in-the-middle attacks extend to serverless environments, with the focus shifting from servers to cloud storage and databases. Exposed secrets, source code, and /tmp directories can be exploited by malicious actors. Prevention strategies encompass meticulous data identification and classification, minimizing storage of sensitive data, robust encryption, HTTPS for endpoint security, and proficient password and key management.

• XML External Entities (XXE): XXE vulnerabilities can persist in older XML processors, potentially leading to the leakage of function code or sensitive data. Mitigate this threat by leveraging cloud-vendor SDKs, diligent supply chain vulnerability scans, rigorous API call vulnerability tests, and the deactivation of entity recognition.

• Access Control Flaws: Serverless architectures, composed of numerous microservices, offer an extended attack surface. Overprivileged functions, when compromised, can potentially enable unauthorized resource access, leading to data compromise or service disruptions. Prevent this by meticulously following the principle of least privilege, automating permission configurations, and diligently adhering to cloud security best practices.

• Security Configuration Gaps: Unlinked triggers, unencrypted files, misconfigured functions, and exposed secrets provide openings for attackers. Exploits in these areas could lead to data breaches, financial losses, DDoS attacks, and reputational harm. Guard against this by regularly scanning for public resources, verifying triggers are appropriately linked, setting optimal timeouts, and adopting automated tools for swift misconfiguration detection.

• Cross-Site Scripting (XSS): XSS attack sources proliferate within serverless environments. In contrast to conventional vulnerabilities primarily stemming from databases, any function trigger becomes a potential XSS entry point. This could lead to identity compromise and unauthorized access. Bolster defense mechanisms by encoding untrusted data prior to transmission and adhering to established frameworks and headers.

• Insecure Deserialization: The use of dynamic languages like Python increases the likelihood of deserialization attacks within serverless implementations. These attacks can trigger arbitrary code execution, leading to data leaks or account compromise. Mitigate this risk by diligently validating serialized objects, enforcing stringent type constraints, scrutinizing third-party libraries for vulnerabilities, and actively monitoring potential attack vectors.

• Using Vulnerable Components: Vulnerabilities stemming from the supply chain are pervasive due to the widespread use of third-party libraries. Exploiting vulnerable code grants attackers an entry point, enabling them to compromise cloud applications. Shield against this through continuous vulnerability scans, meticulous dependency tracking, and limited repository access only to trusted entities.

• Inadequate Logging and Monitoring: Malicious actors thrive in environments devoid of robust monitoring and incident response mechanisms. The absence of comprehensive logging and monitoring allows attackers to operate undetected, potentially realizing their objectives while priming for future assaults. Safeguard against this through cloud vendor-provided monitoring tools that detect anomalies and the deployment of meticulous logging and monitoring solutions covering the entire cloud ecosystem.

Fortifying Your Serverless Ecosystem

Effectively safeguarding serverless environments mandates continuous vulnerability scans and comprehensive configuration management solutions. These measures envelop the application lifecycle, ensuring security from source code development to the culmination of an application’s journey. By embracing proactive security measures and adopting a resolute stance, organizations navigate the dynamic realm of serverless technology with confidence and unwavering resilience.

Contact Black Chili for support in developing and deploying secure serverless cloud workloads.