Bug Bounty Tip: Leveraging Content Security Policy (CSP)

The bug bounty tip of the week comes from Abdelrahman Ali from Egypt. Abdelrahman’s bug bouty tip includes leveraging Content Security Tip (CSP) for maximum impact in bug bounty hunting.

1. Master CSP Basics

Understand that CSP is your ally, designed to thwart attacks. It restricts the execution of scripts, styles, and other resources, making it pivotal in your bug bounty arsenal.

2. Detect Misconfigurations

Search for CSP misconfigurations, which can lead to substantial rewards. Misconfigured policies can allow malicious scripts to run unchecked.

3. Analyze CSP Headers

Probe websites for CSP headers. Look for the “Content-Security-Policy” HTTP response header to unveil potential security gaps.

4. Policy Directives Unveiled

Familiarize yourself with CSP directives; they determine resource origins. Common directives include ‘script-src,’ ‘style-src,’ ‘img-src,’ and more.

5. Script Origins

CSP gives you the power to control script sources. Use ‘script-src’ to allow scripts only from trusted origins like ‘self’ or specific domains.

6. Nonce Usage

CSP provides ‘nonce’ as a safeguard. Include a random nonce in your CSP directive and the script tag; only matching nonces will execute scripts.

Example

html
<script src="https://example.com/script.js" nonce="random-value"></script>
CSP: script-src 'nonce-random-value';

7. Hash Checks

CSP lets you specify trusted script content by hashing. If the script’s hash doesn’t match, it won’t run. Update the hash when script content changes.

Example

html
CSP: script-src 'sha256-hash-value';

8. CSRF Token Protection

Understand how CSP’s ‘img-src’ directive can impact CSRF token security. Inadequate control can lead to token disclosure and potential attacks.

9. Mitigate CSRF Risks

As a bug bounty hunter, help websites protect against CSRF token theft by advising them to restrict ‘img-src’ to trusted sources.

10. Stay Current About CSP

Continuously monitor CSP developments. It’s a dynamic field, and evolving CSP techniques can unlock new bug bounty opportunities.

Thank You for Reading This Week’s Bug Bounty Tip

For more information, please visit Abdelrahman’s GitHub page:

https://0xabdoali.github.io/posts/content-security-policy/

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