SB2017052305 - Red Hat update for samba

Description

This security bulletin contains information about 3 secuirty vulnerabilities.

1) Improper authentication (CVE-ID: CVE-2016-2125)

The vulnerability allows a remote attacker on the local network to bypass Kerberos authentication.

The vulnerability exists due to design error when implementing Kerberos authentication. An attacker with access to local network can place a fake Samba server, intercept a valid general purpose Kerberos "Ticket Granting Ticket" (TGT) and fully impersonate the authenticated user or service.

Successful exploitation of the vulnerability may allow an attacker to bypass authentication process and gain access to otherwise restricted resources and services.

2) Buffer overflow (CVE-ID: CVE-2016-2126)

The vulnerability allows a remote authenticated attacker to escalate privileges.

The vulnerability exists due to a boundary error within Kerberos PAC validation process in winbindd. A remote authenticated attacker can send a specially crafted request to vulnerable Samba server, trigger buffer overflow and execute arbitrary code on the server with elevated privileges.

Successful exploitation of the vulnerability may allow an attacker to execute arbitrary code with elevated privileges.

3) Race condition (CVE-ID: CVE-2017-2619)

The vulnerability allows a remote authenticated user to access otherwise restricted files.

The vulnerability exists due to a race condition when processing symlinks, which lead to files outside the shared folder. An attacker with ability to crate a symlink on a network share can access files not exported under the share definition.

Successful exploitation of the vulnerability may allow an attacker to gain access to potentially sensitive data, but requires that server is under heavy load.

Remediation

Install update from vendor's website.

References

• https://access.redhat.com/errata/RHSA-2017:1265