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Overview

Vendor of the products: TRENDNet (https://www.trendnet.com/)

Reported by: johnawm of HIT-IDS ChunkL Team

Product: TRENDNet TEW-820AP (Version v1.0R)

Affected Version: TRENDNet TEW-820AP 1.01.B01

Firmware: https://downloads.trendnet.com/tew-820ap/firmware/tew-820apv1_(fw1.01b01).zip

image-20221027101724040

Vulnerability Details

A stack overflow vulnerability exists in TrendNet Wireless AC Easy-Upgrader TEW-820AP (Version v1.0R, firmware version 1.01.B01) which may result in remote code execution or denial of service. The issue exists in the binary "boa" which resides in "/bin" folder, and the binary is responsible for serving http connection received by the device. While processing the post reuqest "/boafrm/formWizardPassword", the value of "username" parameter (as shown at line 10 of Figure A) which could be arbitrarily long. The value of this parameter is copied into MIB database with key 182 by “apmib_set” function (as shown at line 13 of Figure A) which could lead to a buffer overflow when it is read and used again.

image-01

Figure A: The decompiled code of function which read and use of the value of parameter "username".

Reproduce and POC

To reproduce the vulnerability, the following steps can be followed:

  1. Start frimware through QEMU system or other methods (real device)
  2. Use the default username and password to login web.
  3. Execute the poc script as follows:
python3 POC_for_formWizardPassword.py 192.168.1.1

Reply by Official

The official TRENDNet has replied on official web site https://www.trendnet.com/support/view.asp?cat=4&id=87

image-20221209112147472