CVE-2024-31461: Plane Project Management SSRF Vulnerability

CVE-2024-31461 Overview

Plane, an open-source project management tool, contains a Server-Side Request Forgery (SSRF) vulnerability in versions prior to 0.17-dev. This vulnerability allows attackers to manipulate server-side requests, potentially enabling unauthorized access to internal network resources that should not be externally accessible. The flaw can be exploited remotely without authentication, making it particularly dangerous for organizations running Plane in environments with sensitive internal services.

Critical Impact

Unauthenticated attackers can leverage this SSRF vulnerability to access internal services, exfiltrate sensitive data from internal APIs, and potentially manipulate internal systems by interacting with backend services that are normally isolated from external access.

Affected Products

• Plane versions prior to 0.17-dev
• Self-hosted Plane installations with network access to internal services
• Plane deployments lacking strict egress filtering

Discovery Timeline

• 2024-04-10 - CVE-2024-31461 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2024-31461

Vulnerability Analysis

This Server-Side Request Forgery (SSRF) vulnerability exists in Plane's handling of user-supplied URLs or parameters that are used to generate server-side HTTP requests. When exploited, the vulnerability allows an attacker to craft malicious requests that cause the Plane server to make requests to arbitrary internal or external destinations. This is classified under CWE-918 (Server-Side Request Forgery).

The impact of this vulnerability is significant and includes unauthorized access to internal services accessible from the server, potential leakage of sensitive information from internal services, and manipulation of internal systems by interacting with internal APIs. Since the vulnerability requires no authentication and is accessible over the network, any exposed Plane instance becomes a potential pivot point into an organization's internal infrastructure.

Root Cause

The root cause of this vulnerability stems from insufficient validation and sanitization of user-controlled input that is subsequently used to construct server-side HTTP requests. The application fails to properly validate URLs or restrict the destinations to which server-side requests can be made, allowing attackers to specify arbitrary targets including internal IP addresses, localhost services, and cloud metadata endpoints.

Attack Vector

The vulnerability is exploitable over the network without requiring any user interaction or prior authentication. An attacker can submit specially crafted requests to the vulnerable Plane application, causing it to make HTTP requests to attacker-specified destinations. Common SSRF attack scenarios include:

The attacker can target internal services by specifying internal IP ranges (e.g., 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16) or localhost/127.0.0.1 addresses. Cloud metadata services (such as 169.254.169.254 for AWS/GCP/Azure) are also prime targets for credential theft. Additionally, the attacker may probe internal network topology or access administrative interfaces that are not exposed to the internet.

For technical details regarding the exploitation mechanism, refer to the GitHub SecurityLab Advisory GHSL-2023-257 and the GitHub Security Advisory GHSA-j77v-w36v-63v6.

Detection Methods for CVE-2024-31461

Indicators of Compromise

• Unusual outbound HTTP requests from Plane servers to internal IP ranges or localhost
• Requests targeting cloud metadata endpoints (e.g., 169.254.169.254)
• High volume of requests to internal services that normally receive no traffic from the Plane application
• Log entries showing access to internal administrative interfaces from the Plane server

Detection Strategies

• Monitor egress traffic from Plane servers for connections to internal network segments or metadata services
• Implement network-level logging to detect SSRF attempts targeting internal resources
• Review Plane application logs for suspicious URL parameters or request patterns
• Deploy web application firewalls (WAF) with SSRF detection rules to identify and block malicious requests

Monitoring Recommendations

• Configure alerting on any outbound connections from Plane to RFC 1918 private address ranges
• Establish baseline network behavior for Plane and alert on deviations
• Monitor for requests containing IP addresses or internal hostnames in URL parameters
• Implement DNS logging to detect resolution of internal hostnames by the Plane application

How to Mitigate CVE-2024-31461

Immediate Actions Required

• Upgrade Plane to version 0.17-dev or later which contains the security patch
• Restrict outgoing network connections from servers hosting Plane to essential services only
• Implement strict input validation on URLs or parameters that are used to generate server-side requests
• Review network segmentation to ensure Plane servers cannot access sensitive internal services

Patch Information

The Plane development team has addressed this vulnerability in version 0.17-dev. The fix was implemented through multiple commits that can be reviewed at commit 4b0ccea and commit d887b78. The associated pull requests #3323 and #3333 contain additional context on the remediation approach.

Workarounds

• Implement network-level egress filtering to restrict outbound connections from Plane servers to only required external services
• Use a web application firewall (WAF) to block requests containing internal IP addresses or suspicious URL patterns
• Deploy Plane in an isolated network segment with no access to sensitive internal services
• Implement allowlist-based URL validation at the application or proxy level to restrict permitted request destinations

# Example: iptables rules to restrict egress from Plane server
# Block access to internal networks and metadata services
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
iptables -A OUTPUT -d 169.254.169.254 -j DROP
iptables -A OUTPUT -d 127.0.0.0/8 -j DROP