Request-url-http-3a-2f-2f169.254.169.254-2flatest-2fmeta Data-2fiam-2fsecurity Credentials-2f __link__ -
http://169.254.169 is a critical endpoint within the AWS Instance Metadata Service (IMDS) used to retrieve temporary security credentials assigned to an EC2 instance. While essential for IAM role authentication, this endpoint is a primary target for Server-Side Request Forgery (SSRF) attacks, which can lead to credential theft and privilege escalation. To mitigate these risks, AWS introduced IMDSv2, which uses a session-oriented, token-based approach to protect against unauthorized metadata access. Implementing IMDSv2 and adopting the principle of least privilege are key security practices for securing this data.
http://169.254.169.254/latest/meta-data/iam/security-credentials/ http://169
This URL is used by AWS instances to retrieve temporary security credentials for making secure requests to AWS services. The breakdown of the URL is: AWS introduced IMDSv2
http://169.254.169.254/: This is the IP address for the Instance Metadata Service. It provides information about the instance it's being run on.latest/: Refers to the latest version of the metadata service.meta-data/: A directory within the metadata service for accessing metadata about the instance.iam/: Refers to Identity and Access Management (IAM) data.security-credentials/: This endpoint returns temporary security credentials for the IAM role attached to the instance.
3. Network-Level Blocking
Use host-based firewalls (iptables, nftables) to restrict access to 169.254.169.254 to only trusted processes, or block it entirely. which uses a session-oriented
iptables -A OUTPUT -d 169.254.169.254 -j DROP
B. Network Ingress Filtering
Implement strict validation on any user-supplied URLs.
- Block Internal IPs: Ensure the application layer rejects requests to private IP ranges (RFC 1918), specifically
169.254.169.254. - URL Decoding: Security controls must decode URLs before validating them to catch obfuscated requests like the one analyzed here.
5. Prevent SSRF at the Application Level
- Validate and sanitize all user-supplied URLs.
- Block access to internal IP ranges (including
169.254.0.0/16). - Use a URL allowlist for fetch requests.
- Disable HTTP redirects for user-supplied URLs.