CB-20240424-001 Severity: Critical Vector: Server-Side Request Forgery (SSRF) / Configuration Leak
It allows applications running on the instance to retrieve temporary AWS IAM credentials (AccessKeyId, SecretAccessKey, and Session Token) without hard-coding keys. The Attack: How SSRF Works
Would you like help writing WAF rules or SSRF mitigation policies for this pattern?
A real-world attack exploiting a callback URL for credentials typically unfolds in a precise chain: To help you secure your systems, let me
: Give your servers only the exact permissions they need to run. To help you secure your systems, let me know: What cloud provider do you use? (AWS, Azure, Google Cloud?) Do you need a code example to block this attack? I can give you exact steps to fix this vulnerability. Share public link
AWS introduced in late 2019 to address the inherent risks of IMDSv1. The old version (v1) was a simple, unauthenticated HTTP endpoint on 169.254.169.254 . Any process on the instance—or any process that could trick the instance into making a request—could retrieve metadata.
The response contains JSON similar to:
An SSRF attack occurs when an attacker forces an application to make an HTTP request to a resource that the application should not normally access.
Title: Something like "Understanding the Dangers of Metadata Service Callback URLs: A Deep Dive into http://169.254.169.254/latest/meta-data/iam/security-credentials/"
An attacker uses a Server-Side Request Forgery (SSRF) vulnerability to execute this attack. SSRF occurs when a backend server fetches data from a user-supplied URL without proper validation. Share public link AWS introduced in late 2019
The URL http://169.254.169.254/latest/meta-data/iam/security-credentials/ is part of the AWS Instance Metadata Service. This service provides information about the EC2 instance that it's running on, including metadata and temporary security credentials.
: Never let users input raw URLs without checking them first.
A proxy that takes a URL and fetches the content. HTML/CSS Validators: Services that parse URL inputs. such as accessing S3 buckets
: With these credentials, an attacker can perform any action the server is authorized to do, such as accessing S3 buckets, modifying databases, or launching new instances. Mitigation: IMDSv2
It is a malicious or test payload targeting AWS metadata credentials. If you encountered this in logs, API requests, or user input – treat it as an active security probe or attack attempt.