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GHSA-2762-657x-v979
No affected components available
Summary
A vulnerability was discovered during a manual security audit of the AlchemyCMS source code. The application uses the Ruby eval() function to dynamically execute a string provided by the resource_handler.engine_name attribute in Alchemy::ResourcesHelper#resource_url_proxy.
Details
The vulnerability exists in app/helpers/alchemy/resources_helper.rb at line 28. The code explicitly bypasses security linting with # rubocop:disable Security/Eval, indicating that the use of a dangerous function was known but not properly mitigated.
Since engine_name is sourced from module definitions that can be influenced by administrative configurations, it allows an authenticated attacker to escape the Ruby sandbox and execute arbitrary system commands on the host OS.
But, for this attack to be possible local file access to the alchemy project or the source on a remote server is necessary in order to manipulate the module config file, though.
PoC (Proof of Concept)
The following standalone Ruby script demonstrates that the eval sink is directly exploitable:
require 'ostruct'
def resource_url_proxy(resource_handler)
if resource_handler.engine_name && !resource_handler.engine_name.empty?
eval(resource_handler.engine_name)
end
end
# Payload to create a file in /tmp directory
payload = "system('touch /tmp/alchemy_rce_verified'); 'main_app'"
handler = OpenStruct.new(engine_name: payload)
resource_url_proxy(handler)
if File.exist?('/tmp/alchemy_rce_verified')
puts "RCE Verified: Command executed successfully."
end
The vulnerability requires local access to the device to be exploited. It is difficult for an attacker to exploit this vulnerability and may require special conditions. An attacker needs high-level or administrative privileges. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a high impact on the confidentiality of the information. There is a high impact on the integrity of the data. There is a high impact on the availability of the system.
Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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