CVE-2020-13379: Grafana SSRF Vulnerability

CVE-2020-13379 Overview

CVE-2020-13379 is a Server-Side Request Forgery (SSRF) vulnerability in the avatar feature of Grafana versions 3.0.1 through 7.0.1. This vulnerability allows any unauthenticated user or client to make Grafana send HTTP requests to arbitrary URLs and return the results to the attacker. The flaw can be exploited to perform internal network reconnaissance and gather sensitive information about the network infrastructure where Grafana is deployed. Additionally, passing malformed URL objects can trigger a SegFault, enabling Denial of Service (DoS) attacks against Grafana instances.

Critical Impact

Unauthenticated attackers can exploit Grafana's avatar feature to perform SSRF attacks for internal network reconnaissance and cause Denial of Service through SegFault crashes.

Affected Products

• Grafana versions 3.0.1 through 7.0.1
• Fedora Project Fedora 31 and 32
• NetApp E-Series Performance Analyzer
• openSUSE Leap 15.2
• openSUSE Backports SLE 15.0 SP1 and SP2

Discovery Timeline

• 2020-06-03 - CVE-2020-13379 published to NVD
• 2020-06-03 - Grafana releases security patches (versions 6.7.4 and 7.0.2)
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2020-13379

Vulnerability Analysis

The vulnerability exists in Grafana's avatar feature implementation, which provides an endpoint that retrieves and renders user avatar images. This endpoint fails to properly validate and restrict the URLs that can be requested, creating a classic SSRF condition. Because the avatar feature is accessible without authentication, any attacker can leverage this endpoint to make Grafana act as a proxy, sending HTTP requests to arbitrary internal or external destinations.

The SSRF vulnerability enables attackers to probe internal network services, potentially accessing cloud metadata endpoints (such as AWS EC2 metadata at 169.254.169.254), internal APIs, databases, and other services that would normally be inaccessible from the external network. This information disclosure can serve as a stepping stone for further attacks.

The secondary impact involves improper URL parsing. When malformed or invalid URL objects are passed to the avatar feature, the application can encounter a SegFault condition, causing Grafana to crash and resulting in Denial of Service.

Root Cause

The root cause is improper access control and insufficient input validation in the avatar feature's URL handling mechanism (CWE-918: Server-Side Request Forgery). The feature lacks authentication requirements and does not implement proper URL allowlisting or blocklisting to restrict which destinations can be requested. This combination of missing authentication and inadequate URL validation creates the SSRF vulnerability.

Attack Vector

The attack vector is network-based and requires no authentication or user interaction. An attacker can craft HTTP requests to the Grafana avatar endpoint with attacker-controlled URLs. When Grafana processes these requests, it fetches the specified URL and returns the response content to the attacker.

A typical exploitation scenario involves an attacker targeting the avatar endpoint with internal IP addresses or cloud metadata URLs to enumerate internal services and extract sensitive configuration data. For DoS attacks, the attacker sends requests with malformed URL structures designed to trigger the SegFault condition in Grafana's URL parsing logic.

Detection Methods for CVE-2020-13379

Indicators of Compromise

• Unusual outbound HTTP requests from Grafana servers to internal IP ranges (e.g., 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16)
• HTTP requests from Grafana to cloud metadata endpoints such as 169.254.169.254
• Repeated requests to the avatar endpoint from external sources with non-standard URL parameters
• Grafana service crashes or SegFault errors in application logs
• High volume of requests to /avatar/ endpoints from unauthenticated sources

Detection Strategies

• Monitor Grafana access logs for requests to avatar endpoints containing internal IP addresses or cloud metadata URLs
• Implement network-level monitoring to detect outbound connections from Grafana to internal services it should not communicate with
• Configure Web Application Firewall (WAF) rules to detect and block SSRF patterns in avatar URL parameters
• Set up alerting for Grafana service crashes or unexpected restarts that may indicate DoS exploitation attempts

Monitoring Recommendations

• Enable detailed access logging for Grafana instances and centralize logs for analysis
• Deploy network traffic analysis tools to monitor Grafana's outbound connections
• Implement endpoint detection solutions to identify unusual process behavior or crashes in Grafana services
• Establish baseline network communication patterns for Grafana and alert on deviations

How to Mitigate CVE-2020-13379

Immediate Actions Required

• Upgrade Grafana to version 6.7.4 or 7.0.2 (or later) immediately
• If immediate patching is not possible, restrict network access to Grafana instances using firewall rules
• Place Grafana behind an authentication proxy to prevent unauthenticated access to vulnerable endpoints
• Review access logs for evidence of exploitation attempts prior to patching

Patch Information

Grafana has released patched versions that address this vulnerability. Organizations should upgrade to Grafana 6.7.4 or 7.0.2 (or later versions) as documented in the Grafana Security Advisory. Additional details are available in the Grafana Community Security Update and the release notes for v6.7.x and v7.0.x.

Workarounds

• Deploy a reverse proxy with authentication in front of Grafana to block unauthenticated requests
• Implement network segmentation to prevent Grafana from accessing sensitive internal services
• Configure egress firewall rules to restrict Grafana's outbound network connectivity
• Use Web Application Firewall rules to block requests containing internal IP addresses or cloud metadata URLs in the avatar parameter

# Example: Restrict Grafana outbound access using iptables
# Block Grafana from accessing cloud metadata endpoint
iptables -A OUTPUT -d 169.254.169.254 -j DROP -m owner --uid-owner grafana

# Restrict Grafana to only communicate with necessary external services
iptables -A OUTPUT -m owner --uid-owner grafana -d 10.0.0.0/8 -j DROP
iptables -A OUTPUT -m owner --uid-owner grafana -d 172.16.0.0/12 -j DROP
iptables -A OUTPUT -m owner --uid-owner grafana -d 192.168.0.0/16 -j DROP