Headline
CVE-2017-12163: Samba - Security Announcement Archive
An information leak flaw was found in the way SMB1 protocol was implemented by Samba. A malicious client could use this flaw to dump server memory contents to a file on the samba share or to a shared printer, though the exact area of server memory cannot be controlled by the attacker.
CVE-2017-12163.html:
==================================================================== == Subject: Server memory information leak over SMB1 == == CVE ID#: CVE-2017-12163 == == Versions: All versions of Samba. == == Summary: Client with write access to a share can cause == server memory contents to be written into a file == or printer. == ====================================================================
=========== Description ===========
All versions of Samba are vulnerable to a server memory information leak bug over SMB1 if a client can write data to a share. Some SMB1 write requests were not correctly range checked to ensure the client had sent enough data to fulfill the write, allowing server memory contents to be written into the file (or printer) instead of client supplied data. The client cannot control the area of the server memory that is written to the file (or printer).
================== Patch Availability ==================
A patch addressing this defect has been posted to
http://www.samba.org/samba/security/
Additionally, Samba 4.6.8, 4.5.14 and 4.4.16 have been issued as security releases to correct the defect. Patches against older Samba versions are available at http://samba.org/samba/patches/. Samba vendors and administrators running affected versions are advised to upgrade or apply the patch as soon as possible.
========== Workaround ==========
As this is an SMB1-only vulnerability, it can be avoided by setting the server to only use SMB2 via adding:
server min protocol = SMB2_02
to the [global] section of your smb.conf and restarting smbd.
======= Credits =======
This problem was reported by Yihan Lian and Zhibin Hu, security researchers with Qihoo 360 GearTeam. Stefan Metzmacher of SerNet and the Samba Team and Jeremy Allison of Google and the Samba Team provided the fix.