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Ubuntu 20.04 LTS: USN-4559-1 Moderate: Samba Authentication Issue

ubuntu
Calendar Grey September 30, 2020
Dist Ubuntu Esm H88
=========================================================================Ubuntu Security Notice USN-
Several security improvements were added to Samba.

Summary

Several security improvements were added to Samba.

Software Description:

- samba: SMB/CIFS file, print, and login server for Unix

Details:

Tom Tervoort discovered that the Netlogon protocol implemented by Samba

incorrectly handled the authentication scheme. A remote attacker could use

this issue to forge an authentication token and steal the credentials of

the domain admin.

While a previous security update fixed the issue by changing the "server

schannel" setting to default to "yes", instead of "auto", which forced a

secure netlogon channel, this update provides additional improvements.

For compatibility reasons with older devices, Samba now allows specifying

an insecure netlogon configuration per machine. See the following link for

examples:

In addition, this update adds additional server checks for the protocol

attack in the client-specified challenge to provide some protection when

'server schannel = no/auto' and avoid the false-positive results when

...

Read the Full Advisory

Topics%20covered

Topics Covered

security advisory remote access samba Ubuntu authentication issue security improvement

Update Instructions

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 20.04 LTS:
  samba                           2:4.11.6+dfsg-0ubuntu1.5

Ubuntu 18.04 LTS:
  samba                           2:4.7.6+dfsg~ubuntu-0ubuntu2.20

Ubuntu 16.04 LTS:
  samba                           2:4.3.11+dfsg-0ubuntu0.16.04.31

In general, a standard system update will make all the necessary changes.

References

https://ubuntu.com/security/notices/USN-4559-1

CVE-2020-1472

Severity
important
Lowest
Low
Medium
High
Critical

September 30, 2020

Topics%20covered

Topics Covered

security advisory remote access samba Ubuntu authentication issue security improvement

Package Information

https://launchpad.net/ubuntu/+source/samba/2:4.11.6+dfsg-0ubuntu1.5
https://launchpad.net/ubuntu/+source/samba/2:4.7.6+dfsg~ubuntu-0ubuntu2.20
https://launchpad.net/ubuntu/+source/samba/2:4.3.11+dfsg-0ubuntu0.16.04.31

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