Subject: [ASA-202009-17] samba: access restriction bypass

Arch Linux Security Advisory ASA-202009-17
==========================================

Severity: Medium
Date    : 2020-09-29
CVE-ID  : CVE-2020-1472
Package : samba
Type    : access restriction bypass
Remote  : Yes
Link    : https://security.archlinux.org/AVG-1236

Summary
=======

The package samba before version 4.13.0-1 is vulnerable to access
restriction bypass.

Resolution
==========

Upgrade to 4.13.0-1.

# pacman -Syu "samba>=4.13.0-1"

The problem has been fixed upstream in version 4.13.0.

Workaround
==========

Ensure you do not have an schannel directive and if you do make sure
it's either = yes or = auto.

Description
===========

A flaw was found in the Microsoft Windows Netlogon Remote Protocol (MS-
NRPC), where it reuses a known, static, zero-value initialization
vector (IV) in AES-CFB8 mode. This flaw allows an unauthenticated
attacker to impersonate a domain-joined computer, including a domain
controller, and possibly obtain domain administrator privileges. The
highest threat from this vulnerability is to confidentiality,
integrity, as well as system availability.

Impact
======

An unauthenticated attacker can gain administrator access through
crafted traffic, if the samba server is configured to run with a
vulnerable schannel directive.

References
==========

https://bugs.archlinux.org/task/67983
https://www.samba.org/samba/security/CVE-2020-1472.html
https://security.archlinux.org/CVE-2020-1472