Headline
Brother MFC-J491DW C1806180757 Password Hash Disclosure
An issue was discovered on Brother MFC-J491DW C1806180757 devices. The printer’s web-interface password hash can be retrieved without authentication, because the response header of any failed login attempt returns an incomplete authorization cookie. The value of the authorization cookie is the MD5 hash of the password in hexadecimal. An attacker can easily derive the true MD5 hash from this, and use offline cracking attacks to obtain administrative access to the device.
[Suggested description]
An issue was discovered on Brother MFC-J491DW C1806180757 devices.
The printer’s web-interface password hash can be retrieved without
authentication, because
the response header of any failed login attempt returns an incomplete
authorization cookie. The value of the authorization cookie is the MD5
hash of the password in hexadecimal. An attacker can easily
derive the true MD5 hash from this, and use offline cracking attacks to
obtain administrative access to the device.
[Vulnerability Type]
Incorrect Access Control
[Vendor of Product]
Brother
[Affected Product Code Base]
MFC-J491DW - C1806180757
[Affected Component]
Web admin panel
[Attack Type]
Remote
[Impact Escalation of Privileges]
true
[Impact Information Disclosure]
true
[Attack Vectors]
An attacker needs to have access to the web interface running on TCP/80 on the device.
[Has vendor confirmed or acknowledged the vulnerability?]
true
[Discoverer]
Konrad Leszcynski, intern at Qbit in cooperation with the Dutch Consumer Organisation
[Reference]
https://global.brother
Use CVE-2019-20457.