: Only permit URLs matching a pre-approved list of domains.
Managed identities eliminate the need for developers to embed hardcoded credentials (like passwords or API keys) into their source code. Instead, the application queries this internal endpoint to request an access token for cloud resources like Azure Key Vault, databases, or storage buckets.
The innocuous-looking string webhook-url-http-3A-2F-2F169.254.169.254-2Fmetadata-2Fidentity-2Foauth2-2Ftoken is a canary in the coal mine—a signal that someone is probing your systems for cloud metadata exposure. Webhooks are a powerful integration tool, but they become a liability when user-supplied URLs are trusted without validation.
Understanding the SSRF Risk: Demystifying the 169.254.169.254 Webhook URL : Only permit URLs matching a pre-approved list of domains
The consequences range from data theft to full infrastructure compromise. For example, Capital One’s 2019 breach (though not exactly this vector) exploited an SSRF to access AWS metadata credentials, leading to the exposure of 100+ million customer records.
The input string is URL-encoded. Decoding the hexadecimal sequences reveals the actual target:
The service does:
The string uses percent-encoding (also called URL encoding) to represent characters that are unsafe or have special meaning in URLs:
Set up alerts for:
: An attacker could steal high-privilege access tokens belonging to the server's identity. The innocuous-looking string webhook-url-http-3A-2F-2F169
"access_token": "eyJ0eXAiOiJKV1QiLCJhbGciOiJSUzI1NiIs...", "expires_in": "86399", "token_type": "Bearer"
Which (Azure, AWS, or GCP) hosts your application?
Here is how to lock it down: