Original release date: January 25, 2003<br>
Last revised: January 27, 2003<br>
<p>A complete revision history can be found at the end of this file.</p>
<li>Microsoft SQL Server 2000
<li>Microsoft Desktop Engine (MSDE) 2000
The CERT/CC has received reports of self-propagating malicious code
that exploits a vulnerability in the Resolution Service of
Microsoft SQL Server 2000 and Microsoft Desktop Engine (MSDE) 2000.
This worm is being referred to as the SQLSlammer, W32.Slammer, and Sapphire worm.
The propagation of this malicious code has caused varied levels of
network degradation across the Internet and the compromise of vulnerable machines.
The worm targeting SQL Server computers is self-propagating malicious
code that exploits the vulnerability described in <a
This vulnerability allows for the execution of arbitrary code on the SQL
Server computer due to a stack buffer overflow.
Once the worm compromises a machine, it will try to propagate
itself. The worm will craft packets of 376-bytes and send them
to randomly chosen IP addresses on port 1434/udp. If the packet is sent
to a vulnerable machine, this victim machine will become infected
and will also begin to propagate. Beyond the scanning activity
for new hosts, the current variant of this worm has no other payload.
Activity of this worm is readily identifiable on a network by the
presence of 376-byte UDP packets. These packets will appear to be
originating from seemingly random IP addresses and destined for port 1434/udp.
Compromise by the worm confirms a system is vulnerable to
allowing a remote attacker to execute arbitrary code as the
local SYSTEM user.
It may be possible for an attacker to subsequently leverage a
local privilege escalation exploit in order to gain Administrator
access to the victim system.
The high volume of 1434/udp traffic generated by hosts
infected with the worm trying to find and compromise other SQL
Server computers may itself lead to performance issues (including possible
denial-of-service conditions) for Internet-connected hosts or
for those computers on networks with compromisecompromised hosts.
<h4>Apply a patch</h4>
Administrators of all systems running Microsoft SQL Server 2000 and MSDE 2000 are encouraged to
review <a href="http://www.cert.org/advisories/CA-2002-22.html">CA-2002-22</a>
and <a href="http://www.kb.cert.org/vuls/id/484891">VU#484891</a>. For
detailed vendor recommendations regarding installing the patch see
SQL Server 2000 and MSDE 2000 both have the vulnerability documented
in <a href="http://www.kb.cert.org/vuls/id/484891">VU#484891</a>. However,
the propagation of the worm requires a process listening on port 1434/udp
to exploit this vulnerability. This precondition is obviously present in
SQL Server 2000. However, not all applications using MSDE 2000 listen
to the network by default. Therefore, only certain MSDE 2000-enabled
applications may be vulnerable.
The following steps are only effective in limiting the damage that
can be done by systems already infected with the worm. They
provide no protection against the initial infection of
systems. As a result, these steps are only recommended <b>in addition
to</b> the preventative steps outlined above.</p>
Ingress filtering manages the flow of traffic as it enters a
network under your administrative control. Servers are typically the
only machines that need to accept inbound traffic from the public
Internet. In the network usage policy of many sites, external hosts
are only permitted to initiate inbound traffic to machines that
provide public services on specific ports. Thus, ingress filtering
should be performed at the border to prohibit externally initiated
inbound traffic to non-authorized services.</p>
Egress filtering manages the flow of traffic as it leaves a network
under your administrative control. There is typically limited need for
machines providing public services to initiate outbound connections to
the Internet. </p>
In the case of this worm, employing ingress and
egress filtering can help prevent compromised systems on your network
from attacking systems elsewhere. Blocking UDP datagrams with
both source or destination ports 1434 from entering or leaving your network
reduces the risk of external infected systems communicating with
infected hosts inside your network.</p>
<h4>Recovering from a system compromise</h4>
<p>If you believe a system under your administrative control has been compromised, please follow the steps outlined in</p>
<dl><dd><a href="http://www.cert.org/tech_tips/win-UNIX-system_compromise.html">Steps for Recovering from a UNIX or NT System Compromise</a></dd></dl>
<p>The CERT/CC is interested in receiving reports of this activity. If
machines under your administrative control are compromised, please
send mail to <a href="mailto:firstname.lastname@example.org?subject=%5BCERT%2335663%5D">email@example.com</a> with the following text included in the
subject line: "<a href="mailto:firstname.lastname@example.org?subject=%5BCERT%2335663%5D">[CERT#35663]</a>".</p>
<p>Feedback can be directed to the author: <a href="mailto:email@example.com?subject=CA-2003-04%20Feedback%20">Roman Danyliw</a>
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<h2>CERT/CC Contact Information</h2>
<dl><b>Email:</b> <a href="mailto:firstname.lastname@example.org">email@example.com</a><br>
<b>Phone:</b> +1 412-268-7090 (24-hour hotline)<br>
<b>Fax:</b> +1 412-268-6989<br>
CERT Coordination Center<br>
Software Engineering Institute<br>
Carnegie Mellon University<br>
Pittsburgh PA 15213-3890<br>
CERT/CC personnel answer the hotline 08:00-17:00 EST(GMT-5) / EDT(GMT-4)
Monday through Friday; they are on call for emergencies during other
hours, on U.S. holidays, and on weekends.
We strongly urge you to encrypt sensitive information sent by
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If you prefer to use DES, please call the CERT hotline for more
<h4>Getting security information</h4>
CERT publications and other security information are available from
our web site
To subscribe to the CERT mailing list for advisories and bulletins, send email to
<a href="mailto:firstname.lastname@example.org">email@example.com</a>. Please include in the body of your
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<p>Copyright 2003 Carnegie Mellon University.</p>
January 25, 2003: Initial release
January 26, 2003: Updated VU# information, packet size, MS Advisory link
January 27, 2003: MSDE 2000
October 25, 2021: fixed typo in Impact "compromised hosts"