👉 Overview
👀 What ?
Server Side Request Forgery (SSRF) is a web security vulnerability that allows an attacker to induce the server-side application to make HTTP requests to an arbitrary domain of the attacker's choosing. In a typical SSRF attack, the attacker might cause the server to make a connection back to itself, or to other web-based services within the organization’s infrastructure, or to external third-party systems.
🧐 Why ?
SSRF is a significant security concern in a cloud environment as it can be used to target internal systems that are not normally accessible to an attacker from the external network. An attacker can leverage SSRF vulnerabilities to read, update and delete data from these systems. It’s important to understand and mitigate SSRF vulnerabilities to protect sensitive systems from unauthorized access and manipulation.
⛏️ How ?
To prevent SSRF attacks in a cloud environment, ensure your applications only accept server-side requests from trusted sources. Apply the principle of least privilege to server-side requests - only allow access to necessary resources. Use allow-lists for server-side request destinations and validate or sanitize user input. Regularly review and update your security configurations and perform regular vulnerability assessments.
⏳ When ?
The use of SSRF attacks has been on the rise in the past few years, particularly with the increasing adoption of cloud services. It has been reported in popular web applications like Google, Facebook, and Instagram.
⚙️ Technical Explanations
In a cloud environment, SSRF can be particularly dangerous because of the additional resources that are available in the cloud. For example, cloud services often provide metadata services that can be accessed by any code running on the server. A successful SSRF attack could potentially allow an attacker to access sensitive metadata, which could include credentials for other cloud services. The attack takes place when a user can supply or modify a URL which the code running on the server will read or submit data to, and by carefully selecting the URLs, the attacker may be able to read server configuration such as AWS metadata, connect to internal services like http enabled databases or perform post requests towards internal services which are not intended to be exposed.