CVE-2024-5526 Overview
CVE-2024-5526 is a Server-Side Request Forgery (SSRF) vulnerability affecting Grafana OnCall, a popular on-call management tool designed to streamline incident response workflows for engineering teams. This vulnerability exists within the webhook functionality of Grafana OnCall and allows unauthenticated attackers to forge server-side requests, potentially leading to unauthorized access to internal resources and sensitive data exfiltration.
Critical Impact
This SSRF vulnerability enables attackers to make arbitrary requests from the server, potentially accessing internal services, cloud metadata endpoints, and sensitive infrastructure components that are not otherwise accessible from the external network.
Affected Products
- Grafana OnCall versions 1.1.37 through 1.5.1
- Grafana OnCall deployments utilizing webhook functionality
- Self-hosted and cloud-based Grafana OnCall installations within the affected version range
Discovery Timeline
- 2024-06-05 - CVE-2024-5526 published to NVD
- 2024-11-21 - Last updated in NVD database
Technical Details for CVE-2024-5526
Vulnerability Analysis
The vulnerability resides in the webhook functionality of Grafana OnCall, specifically in how the application processes and validates webhook URLs. When processing webhook configurations, the application fails to properly validate and sanitize user-supplied URLs before making server-side HTTP requests. This allows an attacker to craft malicious webhook configurations that target internal resources, cloud metadata services, or other protected endpoints.
The weakness is classified as CWE-918 (Server-Side Request Forgery), which occurs when web applications fetch resources from user-specified URLs without adequate validation. In the context of Grafana OnCall, this means an attacker can leverage the webhook feature to pivot into internal network segments or access services that trust requests originating from the Grafana OnCall server.
Root Cause
The root cause of this vulnerability is insufficient URL validation in the webhook processing logic. The application does not implement adequate safeguards to prevent webhooks from targeting internal IP addresses, localhost, cloud metadata endpoints (such as 169.254.169.254), or other sensitive network locations. Without proper URL scheme restrictions, IP address blocklisting, and DNS rebinding protections, the webhook functionality becomes an attack vector for SSRF exploitation.
Attack Vector
This vulnerability is exploitable over the network without requiring authentication or user interaction. An attacker can exploit CVE-2024-5526 by:
- Accessing the Grafana OnCall webhook configuration interface
- Creating or modifying a webhook with a malicious target URL pointing to internal resources
- Triggering the webhook execution to force the server to make requests to the attacker-specified destination
- Capturing sensitive data from internal services, cloud metadata endpoints, or using the server as a proxy to access otherwise protected resources
The vulnerability can be exploited to access cloud provider metadata services (AWS, GCP, Azure), internal APIs, databases, and other services that may trust requests from the Grafana OnCall server's IP address. For additional technical details, refer to the Grafana Security Advisory CVE-2024-5526.
Detection Methods for CVE-2024-5526
Indicators of Compromise
- Webhook configurations containing internal IP addresses (e.g., 10.x.x.x, 172.16.x.x, 192.168.x.x)
- Webhook URLs targeting cloud metadata endpoints such as http://169.254.169.254/
- Unusual outbound HTTP requests from the Grafana OnCall server to internal services
- Webhook configurations using non-standard ports or targeting localhost addresses
Detection Strategies
- Monitor Grafana OnCall webhook configurations for suspicious URL patterns including internal IP ranges and metadata service addresses
- Implement network-level detection for outbound requests from Grafana OnCall servers to internal resources or cloud metadata endpoints
- Review application logs for webhook execution failures or unexpected response patterns indicating SSRF attempts
- Deploy web application firewall (WAF) rules to detect SSRF attack patterns in webhook-related API requests
Monitoring Recommendations
- Enable verbose logging for webhook creation and execution events in Grafana OnCall
- Configure network monitoring to alert on connections from Grafana OnCall servers to sensitive internal endpoints
- Implement egress filtering and monitor for attempts to bypass network controls
- Regularly audit webhook configurations for compliance with security policies
How to Mitigate CVE-2024-5526
Immediate Actions Required
- Upgrade Grafana OnCall to version 1.5.2 or later immediately
- Audit all existing webhook configurations for potentially malicious URLs
- Implement network segmentation to limit the Grafana OnCall server's access to internal resources
- Apply egress filtering to restrict outbound connections from the Grafana OnCall server
Patch Information
Grafana has released version 1.5.2 which addresses this SSRF vulnerability. Organizations should upgrade to this version or later as soon as possible. The patch implements proper URL validation and restrictions on webhook targets to prevent SSRF attacks. For detailed patch information, consult the Grafana Security Advisory CVE-2024-5526.
Workarounds
- Implement network-level egress filtering to block outbound requests to internal IP ranges and cloud metadata endpoints from the Grafana OnCall server
- Deploy a reverse proxy with URL validation in front of the Grafana OnCall webhook functionality
- Restrict access to webhook configuration capabilities to trusted administrators only
- Use firewall rules to limit the Grafana OnCall server's ability to connect to sensitive internal services
# Example iptables rules to block access to cloud metadata endpoints
iptables -A OUTPUT -d 169.254.169.254 -j DROP
iptables -A OUTPUT -d 10.0.0.0/8 -j DROP
iptables -A OUTPUT -d 172.16.0.0/12 -j DROP
iptables -A OUTPUT -d 192.168.0.0/16 -j DROP
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