Samba: Execution of arbitrary code

Background

Samba is a suite of SMB and CIFS client/server programs for UNIX.

Description

Two vulnerabilities have been reported in nmbd. Alin Rad Pop (Secunia Research) discovered a boundary checking error in the reply_netbios_packet() function which could lead to a stack-based buffer overflow (CVE-2007-5398). The Samba developers discovered a boundary error when processing GETDC logon requests also leading to a buffer overflow (CVE-2007-4572).

Impact

To exploit the first vulnerability, a remote unauthenticated attacker could send specially crafted WINS “Name Registration” requests followed by a WINS “Name Query” request. This might lead to execution of arbitrary code with elevated privileges. Note that this vulnerability is exploitable only when WINS server support is enabled in Samba. The second vulnerability could be exploited by sending specially crafted “GETDC” mailslot requests, but requires Samba to be configured as a Primary or Backup Domain Controller. It is not believed the be exploitable to execute arbitrary code.

Workaround

To work around the first vulnerability, disable WINS support in Samba by setting “wins support = no” in the “global” section of your smb.conf and restart Samba.

Resolution

All Samba users should upgrade to the latest version:

 # emerge --sync
 # emerge --ask --oneshot --verbose ">=net-fs/samba-3.0.27a"

The first vulnerability (CVE-2007-5398) was already fixed in Samba 3.0.26a-r2.