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Overflow in Windows Locator Service
A buffer overflow in the Windows Locator service may
make it possible for a remote attacker to execute arbitrary
code on a vulnerable system by sending an overly large
request to the Windows Locator service.
Microsoft describes the Windows Locator service as "a
name service that maps logical names to network-specific
A client that is going to make a Remote Procedure Call
(RPC) can call the Locator service to resolve a logical
name for a network object to a network-specific name
for use in the RPC. For example, if a print server has
the logical name "laserprinter", an RPC client
could call the Locator service to find out the network-specific
name that mapped to "laserprinter". The RPC
client uses the network-specific name when it makes
the RPC call to the service.
This service is enabled and running by default on Windows
2000 domain controllers and Windows NT 4.0 domain controllers.
A remote attacker may be able to execute arbitrary code
on a vulnerable system, or cause the Windows Locator
service to fail. An attacker who is able to compromise
a domain controller might be able to cause the compromised
domain controller to trust the attacker's domain.
Microsoft Windows NT 4.0, Windows NT 4.0, Terminal Server
Edition, Windows 2000, Windows XP
Microsoft has provided the following information to
assist in downloading the appropriate patch for your
Windows NT 4.0, Windows NT 4.0 Terminal Server Edition,
Windows 2000, Windows XP:
Until a patch can be applied, you may wish to disable
the Windows Locator service. To determine if the Windows
Locator service is running, check the following:
The status of the 'Remote Procedure Call (RPC) Locator'
service and how it is started (automatically or manually)
can be viewed in the Control Panel. For Windows 2000
and Windows XP, use Control Panel | Administrative Tools
| Services, and on Windows NT 4.0, use Control Panel
It is also possible to determine the status of the Locator
service from the command line by entering: net start
A list of services will be displayed. If 'Remote Procedure
Call (RPC) Locator' appears in the list, then the locator
service is running.
To disable the Windows Locator service:
An administrator can disable the Locator service by
setting the RpcLocator service status to "disabled"
in the services control panel.
The service can also be stopped via the command line
using the sc.exe program, which ships with Windows XP
and is included as part of the Windows 2000
Resource Kit. The following command will stop the service:
sc stop RpcLocator
To disable the service using the command line tool,
use the following: sc config RpcLocator start= disabled
Restrict access to NetBIOS
You may want to block access to NetBIOS from outside
your network perimeter, specifically by blocking access
to ports 139/TCP and 445/TCP. This will limit your exposure
to attacks. However, blocking at the network perimeter
would still allow attackers within the perimeter of
your network to exploit the vulnerability. It is important
to understand your network's configuration and service
requirements before deciding what changes are appropriate.
As a best practice, it is recommended to disable all
services that are not explicitly required. Before deciding
to disable the Windows Locator service, carefully consider
your service requirements.
Please also note that Microsoft is actively deploying
the patches for this vulnerability via Windows Update.
Buffer Overflows in ISC DHCPD
The Internet Software Consortium (ISC) has discovered
several buffer overflow vulnerabilities in their implementation
of DHCP (ISC DHCPD). These vulnerabilities may allow
remote attackers to execute arbitrary code on affected
The Dynamic Host Configuration Protocol (DHCP) provides
a framework for passing configuration information to
hosts on a TCP/IP network. In addition to supplying
hosts with network configuration data, ISC DHCPD allows
the DHCP server to dynamically update a DNS server,
eliminating the need for manual updates to the name
server configuration. Support for dynamic DNS updates
is provided by the NSUPDATE feature.
During an internal source code audit, developers from
the ISC discovered several vulnerabilities in the error
handling routines of the minires library, which is used
by NSUPDATE to resolve hostnames. These vulnerabilities
are stack-based buffer overflows that may be exploitable
by sending a DHCP message containing a large hostname
Note: Although the minires library is derived from the
BIND 8 resolver library, these vulnerabilities do not
affect any current versions of BIND.
Remote attackers may be able to execute arbitrary code
with the privileges of the user running ISC DHCPD.
Systems running ISC DHCPD versions 3.0 through 3.0.1RC10,
The ISC has addressed these vulnerabilities in versions
3.0pl2 and 3.0.1RC11 of ISC DHCPD.
Disable dynamic DNS updates (NSUPDATE)
As an interim measure, the ISC recommends disabling
the NSUPDATE feature on affected DHCP servers.
Block external access to DHCP server ports
It is possible to limit exposure to these vulnerabilities
by restricting external access to affected DHCP servers
on the following ports:
bootps 67/tcp # Bootstrap Protocol Server
bootps 67/udp # Bootstrap Protocol Server
bootpc 68/tcp # Bootstrap Protocol Client
bootpc 68/udp # Bootstrap Protocol Client
the DHCP service
As a general rule, it is recommended disabling any service
or capability that is not explicitly required. Depending
on your network configuration, you may not need to use
Debian has updated their distribution with DSA 231.
For the stable distribution (woody) this problem has
been fixed in version 3.0+3.0.1rc9-2.1.
The old stable distribution (potato) does not contain
For the unstable distribution (sid) this problem has
been fixed in version 3.0+3.0.1rc11-1.
Internet Software Consortium
They have a patched version of 3.0 available (3.0pl2)
and a new release candidate for the next bug-fix release
(3.0.1RC11). Both of these new releases are available
Red Hat Inc.
Red Hat distributes a vulnerable version of ISC DHCP
in Red Hat Linux 8.0. Other distributions of Red Hat
Linux are not vulnerable to these issues. New DHCP packages
are available along with an advisory at the URL below.
Users of the Red Hat Network can update their systems
using the 'up2date' tool.