Epson WorkForce Multi-Function Printer Firmware Update POST Request privileges management

Summaryinfo

A vulnerability labeled as critical has been found in Epson WorkForce Multi-Function Printer. Affected by this vulnerability is an unknown functionality of the component Firmware Update Handler. Executing a manipulation as part of POST Request can lead to privileges management. In addition, an exploit is available. The affected component should be upgraded.

Detailsinfo

A vulnerability was found in Epson WorkForce Multi-Function Printer (Printing Software) (the affected version unknown). It has been declared as critical. This vulnerability affects an unknown part of the component Firmware Update Handler. The manipulation as part of a POST Request leads to a privileges management vulnerability. The CWE definition for the vulnerability is CWE-269. The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor. As an impact it is known to affect confidentiality, integrity, and availability.

The weakness was presented 09/24/2016 by Ralf Spenneberg as OS-S Security Advisory 2016-19 as not defined mailinglist post (Bugtraq). The advisory is available at seclists.org. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. Technical details are unknown but a public exploit is available. This vulnerability is assigned to T1068 by the MITRE ATT&CK project. The advisory points out:

Epson multi function printers support firmware-Updates via USB and HTTP. When using HTTP, the update is initialized with a GET request and the firmware is uploaded via a POST request. No authorization is required. An attacker can exploit this unauthorized mechanism using Cross-Site-Request-Forgery (CSRF). Because the firmware itself is neither encrypted nor digitaly signed an attacker can create malicious firmware images including backdoors and other malware.

A public exploit has been developed by Ralf Spenneberg in HTTP POST Request and been published immediately after the advisory. It is possible to download the exploit at seclists.org. It is declared as proof-of-concept. The vulnerability was handled as a non-public zero-day exploit for at least 121 days. During that time the estimated underground price was around $0-$5k. The code used by the exploit is:

POST /DOWN/FIRMWAREUPDATE/ROM1 HTTP/1.1\r\n
Accept: */*\r\n
Content-Type: multipart/form-data; boundary=---------------------------	EPSONOP2HANAOKAGROUP1999\r\n
Content-Length: xxx\r\n
Connection: Keep-Alive\r\n
\r\n
---------------------------EPSONOP2HANAOKAGROUP1999\r\n
Content-Disposition: form-data; name=``fname''; filename=``/DUMMY.DAT''\r\n
Content-Type: application/octet-stream\r\n
\r\n
insert firmware here
\r\n
---------------------------EPSONOP2HANAOKAGROUP1999--\r\n

Exploit code just needs to mimic the HTTP update mechanism directly or using CRSF. With a basic understanding of the firmware format and checksums, an attacker can create malicious firmware images including backdoors and malware for the devices. Vulnerable

Upgrading eliminates this vulnerability. A possible mitigation has been published before and not just after the disclosure of the vulnerability.

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Productinfo

Type

• Printing Software

Vendor

• Epson

Name

• WorkForce Multi-Function Printer

CPE 2.3info

• 🔍

CPE 2.2info

• 🔍

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