Ruby Code Vulnerability Analysis: ConfirmSnsSubscription RCE

渗透技巧 11个月前 admin
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Identifying and Addressing Security Concerns in a Ruby SNS Subscription Confirmation Class

Ruby Code Vulnerability Analysis: ConfirmSnsSubscription RCE
Designed by Author

Overview

Vulnerable Code Snippet

module Jobs

  class ConfirmSnsSubscription < ::Jobs::Base
    sidekiq_options retry: false

    def execute(args)
      return unless raw = args[:raw].presence
      return unless json = args[:json].presence
      return unless subscribe_url = json["SubscribeURL"].presence

      require "aws-sdk-sns"
      return unless Aws::SNS::MessageVerifier.new.authentic?(raw)

      # confirm subscription by visiting the URL
      open(subscribe_url)
    end

  end

end
open(subscribe_url)

Findings

  1. Lack of Input Validation:
  • Inputs like subscribe_urlraw, and json don’t get the required validation and sanitization in the code. This may result in a number of security problems, such as code injection and malicious URL execution.
  • Without any validation or sanitization, the open(subscribe_url) statement opens and accesses the subscribe_url. RCE may be caused by an attacker using the subscribe_url option to run arbitrary code on the server.
  • There are no facilities for managing errors in the code. The code will not be handled correctly if an error, such as a network problem or a URL with a mistake, happens while it is being run, which might result in crashes or strange behaviour.
  • The Aws::SNS::MessageVerifier is imported from the aws-sdk-sns gem without checking the gem’s integrity or specifying a particular gem version. Utilising old or vulnerable dependencies might result in danger.

Compliant Solution

require "open-uri"

module Jobs
  class ConfirmSnsSubscription < ::Jobs::Base
    sidekiq_options retry: false

    def execute(args)
      return unless raw = args[:raw].presence
      return unless json = args[:json].presence
      return unless subscribe_url = json["SubscribeURL"].presence

      require "aws-sdk-sns"
      return unless Aws::SNS::MessageVerifier.new.authentic?(raw)

      # Fixed: Validate and sanitize the subscribe_url before opening
      if safe_url?(subscribe_url)
        open(sanitize_url(subscribe_url))
      else
        raise "Invalid subscribe_url"
      end
    end

    private

    def safe_url?(url)
      # Implement URL validation logic here, e.g., using a whitelist approach
      # to allow only trusted and expected URLs.
      # Example validation logic:
      whitelist = ["https://trusted-example.com", "https://another-trusted-url.com"]
      whitelist.include?(url)
    end

    def sanitize_url(url)
      # Implement URL sanitization logic here, if required.
      # This step is to ensure the URL is safe and free from any potentially malicious parts.
      # You may use appropriate methods or libraries to sanitize the URL.
      url
    end
  end
end

Conclusion

 

原文始发于ASWIN K V:Ruby Code Vulnerability Analysis: ConfirmSnsSubscription RCE

版权声明:admin 发表于 2023年5月5日 下午9:32。
转载请注明:Ruby Code Vulnerability Analysis: ConfirmSnsSubscription RCE | CTF导航

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