Lepin EP-KP001 KP001_V19 Authentication Bypass Vulnerability

Product:                   EP-KP001
Manufacturer:              Lepin
Affected Version(s):       KP001_V19
Tested Version(s):         KP001_V19
Vulnerability Type:        Violation of Secure Design Principles (CWE-657)
Risk Level:                High
Solution Status:           Open
Manufacturer Notification: 2022-04-12
Solution Date:             -
Public Disclosure:         2022-06-10
CVE Reference:             CVE-2022-29948
Author of Advisory:        Matthias Deeg (SySS GmbH)

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Overview:

The Lepin EP-KP001 is a USB flash drive with AES-256 hardware encryption
and a built-in keypad for passcode entry.

The manufacturer describes the product as follows (see [1]):

"[Safeguard Your Sensitive DATA] With Military Grade Full-disk 256-bit
AES XTS Hardware Encryption to protect your important files. All your
data is protected by hardware encryption, so no one can access your
data without knowing the password."

Due to an insecure design, the Lepin EP-KP001 flash drive is vulnerable
to an authentication bypass attack which enables an attacker to gain
unauthorized access to the stored encrypted data.

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Vulnerability Details:

When analyzing the USB flash drive Lepin EP-KP001, Matthias Deeg found
out that it uses an insecure hardware design which allows an attacker
to bypass the password-based user authentication.

The Lepin EP-KP001 consists of the following four main parts:

1. An unknown NAND flash memory chip
2. An Alcor Micro flash disk controller (AU6989SNBL-GTD)
3. An unknown microcontroller (unkmarked chip) used as keypad controller
4. A high-speed analog switch (SGM7222)

The encrypted disk partition with the stored user data can be unlocked
by entering the correct passcode via the keypad and pressing the
"unlock" button.

Due to the performed analysis, the password-based user authentication
via a passcode comprised of 6 to 14 digits is performed by the unknown
microcontroller.

By replacing this unknown microcontroller on a target device with one
from an attacker-controlled Lepin EP-KP001 whose passcode was known, it
was possible to successfully unlock the targeted Lepin EP-KP001 USB
flash drive and to gain unauthorized access to the stored data in
cleartext.

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Proof of Concept (PoC):

A successful authentication bypass attack could be performed via the
following steps:

1. Set a passcode on an attacker-controlled Lepin EP-KP001.

2. Desolder the unmarked microcontroller from the attacker-controlled
    device.

3. Desolder the unmarked microcontroller from the targeted Lepin
    EP-KP001.

4. Solder the unmarked microcontroller from the attacker-controlled
    device on the targeted device.

5. Unlock the targeted device with the initially set and known passcode.

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Solution:

SySS is not aware of a security fix for the described security issue.

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Disclosure Timeline:

2022-04-12: Vulnerability reported to manufacturer
2022-06-10: Public release of security advisory

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References:

[1] Product website for Lepin EP-KP001
 
https://www.amazon.com/Encrypted-Password-Aluminum-Portable-Protected/dp/B06W5H9GP7/
[2] SySS Security Advisory SYSS-2022-024
 
https://www.syss.de/fileadmin/dokumente/Publikationen/Advisories/SYSS-2022-024.txt
[4] SySS GmbH, SySS Responsible Disclosure Policy
     https://www.syss.de/en/responsible-disclosure-policy