SB2016122005 - Multiple vulnerabilities in 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) Integer underflow (CVE-ID: CVE-2016-2123)

The vulnerability allows a remote authenticated user to compromise vulnerable server.

The vulnerability exists due to integer underflow within ndr_pull_dnsp_name routine when processing dnsRecord attribute in LDAP requests. A remote authenticated attacker can send a specially crafted LDAP request to the affected server, trigger heap-based buffer overflow and execute arbitrary code on the target sever.

Successful exploitation of the vulnerability may allow an attacker to compromise vulnerable server.

Remediation

Install update from vendor's website.

References

• https://www.samba.org/samba/security/CVE-2016-2125.html
• https://www.samba.org/samba/security/CVE-2016-2126.html
• https://www.samba.org/samba/security/CVE-2016-2123.html