Name: Ejs AND Underscore Scanner

Ejs is a simple templating language that lets you generate HTML markup with plain JavaScript. It is widely used in Node.js web applications to manage and inject dynamic content on web pages efficiently. Underscore is a JavaScript library that provides utility functions for common programming tasks. Ejs and Underscore are used by developers to streamline the creation of web applications by allowing for smooth integration and management of reusable code components. Developers appreciate their simplicity and versatility, which support rapid application development workflows. Due to their ease of use and integration capabilities, these tools are popular choices for developing interactive web applications. Organizations leveraging these technologies benefit from their ability to manage dynamic content integration seamlessly.

Server-side template injection occurs when user inputs are directly embedded in templates without proper sanitization. Attackers exploit this vulnerability by injecting malicious code that gets executed on the server-side. In web applications using Ejs and Underscore, the failure to properly handle template elements can lead to remote code execution. This kind of vulnerability can allow attackers to tamper with templates in real-time, leading to severe security implications. The main risk arises from improper validation of user-supplied content that interacts with the server-side template engines. When exploited, it can provide attackers unauthorized control and access to sensitive backend functionalities.

The SSTI vulnerability in Ejs and Underscore emerges primarily from unsanitized input handling in templated responses. Attackers can exploit this by injecting syntax that the server's template engine interprets as executable code. Typically, vulnerabilities may reside in query parameters or any input fields that format and process dynamic content. The template injection may involve altering key-value pairs that are processed by the server. This manipulation can invoke unintended server-side operations, or even allow attackers to exfiltrate sensitive information. The presence of syntax elements like <%=' within template directives can indicate vulnerability to SSTI.

Exploiting SSTI can lead to unauthorized code execution, enabling potential full system compromise. Malicious actors might execute arbitrary commands, inject further malicious payloads, or deface web applications. The most critical consequences include unauthorized access to sensitive data and administrative functions. Prolonged compromise can affect database integrity and lead to data theft or loss. SSTI vulnerabilities can significantly undermine trust in web applications, resulting in reputational damage to the affected organization. Additionally, attackers could use the compromised system as a pivot point for lateral network movement, escalating the impact.

REFERENCES

• https://ejs.co/
• https://underscorejs.org/
• https://medium.com/@0xAwali/template-engines-injection-101-4f2fe59e5756