Mitigation and remediation steps Immediate (0–24 hours)
to AWS resources (S3, EC2, RDS, etc.). Exfiltrate data from sensitive storage buckets. Launch further attacks within the cloud infrastructure. 4. Risks and Impact
Access to customer data stored in cloud services.
Deploy a WAF with rules designed to detect common LFI and SSRF patterns, such as the presence of file:// , /etc/passwd , or .aws/credentials in URL parameters.
To ensure your application remains protected, verify whether any of your public webhooks or authentication flows accept arbitrary redirect inputs. I can help you evaluate your code architecture if you share or clarify how your servers currently authenticate to AWS . Share public link
Below is a draft post formatted for a technical audience (like on Security Blog ) that explains this vulnerability.
Ensure that user-supplied callback URLs are properly sanitized and that any wildcard characters ( * , ? , [ , ] ) are rejected or escaped. Never pass unsanitized user input to filesystem or URI-fetching functions.
For further security testing, the OWASP SSRF Prevention Cheat Sheet provides comprehensive guidance on avoiding this type of vulnerability.
SSRF occurs when a web application takes a user-supplied URL (often a callback URL or preview link) and makes a backend server-to-server request to that destination without adequate validation. If the application’s HTTP parsing engine accepts the file:// scheme rather than strictly enforcing https:// , the server will query its own internal system. 2. Open Redirect / Weak Callback Validation
Most file URI attacks target a specific path, e.g., file:///etc/passwd . The inclusion of * indicates the attacker expects the vulnerable code to perform or path expansion . For example:
Context and risk
If an attacker successfully extracts this file via an SSRF/LFI exploit: Credentials - Boto3 1.43.18 documentation
The attack typically targets applications that do not properly validate user-supplied URLs. Here is the step-by-step breakdown of how this exploit manifests:
The core issue stems from an application failing to restrict the protocol scheme and destination path of a user-controlled callback parameter. Decoding the Target String
The two colleagues shared a laugh, and the mysterious callback URL was relegated to a cautionary tale in the Eclipse project's history.
If callback_url equals file:///home/*/.aws/credentials , urlopen will read the local file (assuming the wildcard is resolved or the file exists). The content is then exfiltrated.
The /home/*/.aws/credentials file contains essential information, including: