Alerts

Internet Security systems Security Alert
January 25, 2003

Microsoft SQL Slammer Worm Propagation

Synopsis:

ISS X-Force has learned of a worm that is spreading via Microsoft SQL
servers. The worm is responsible for large amounts of Internet traffic as
well as millions of UDP/IP probes at the time of this alert's publication.
This worm attempts to exploit MS/SQL servers vulnerable to the SQL Server
Resolution service buffer overflow (CVE CAN-2002-0649). Once a vulnerable
computer is compromised, the worm will infect that target, randomly select a
new target, and resend the exploit and propagation code to that host.

Impact:

Although the Slammer worm is not destructive to the infected host, it does
generate a damaging level of network traffic when it scans for additional
targets. A large amount of network traffic is created by the worm, which
scans random IP addresses for vulnerable servers. Billions of attacks have
been detected in the last 12 hours from various industry sources, including
ISS MSS (Managed Security Services). ISS has received reports that several
major national ISPs were either experiencing severe latency or were completely
unreachable during the same time frame.

Affect Versions:

Microsoft SQL Server 2000
Microsoft Desktop Engine (MSDE) 2000

Note: Unpatched or base installations older than SP3 are vulnerable.

Description:

The Slammer worm propagates via Microsoft SQL installations without patches
from Microsoft Security Bulletin MS02-039 or higher. The main function of the
Slammer worm is to continue propagation. No DDOS or backdoor functionality is
incorporated into the worm.  Infection can be removed with a reboot, however
without protection in place, it is likely that vulnerable servers will be
quickly re-infected.

The Slammer worm loads Kernel32.dll and WS2_32.dll and then calls GetTickCount
which is used as a seed for a random IP address routine. This routine then
continuously sends 376 bytes of exploit and propagation code across port
1434/UDP until the SQL Server process is shut down. The Slammer worm does not
prefer to scan local subnet addresses like the Nimda worm. This will limit
the speed of propagation across local networks, but this scanning method
generates large amounts of traffic that can overwhelm networks.

The Slammer worm simply seeks to replicate itself and does not try to further
compromise servers or retain access to compromised hosts. The Slammer worm does
not infect or modify files, it only exists in memory.

Recommendations:

ISS X-Force recommends that system administrators immediately take steps to
protect their networks. To remove the infection, apply the necessary patches
listed below and restart the server. This action will remove the worm from
memory.

The following ISS updates address the issues described in this alert. These
updates are available from the ISS Download center (http://www.iss.net/download)

RealSecure Network Sensor XPU 20.4 and XPU 5.3 (available 9/17/02) or greater.

Internet Scanner XPU 6.15 (available 7/25/02).

Additionally ISS X-Force recommends blocking UDP port 1433 and 1434 traffic to
protect SQL Server databases with a firewall or packet filter.

Microsoft SQL Server customers should refer to the following address for
information and securing Microsoft SQL Server against this buffer overflow:
http://www.microsoft.com/technet/security/bulletin/MS02-039.asp.

Additional Information:

The Common Vulnerabilities and Exposures (CVE) project has assigned the name
CAN-2002-0649 to this issue. This is a candidate for inclusion in the CVE
list http://cve.mitre.org), which standardizes names for security problems.

NGSSoftware Insight Security Research Advisory #NISR25072002, "Unauthenticated
Remote Compromise in MS SQL Server 2000" at:
http://www.ngssoftware.com/advisories/mssql-udp.txt

Microsoft Security Bulletin MS02-039, "Buffer Overruns in SQL Server 2000
Resolution Service Could Enable Code Execution (Q323875)" at
http://www.microsoft.com/technet/security/bulletin/MS02-039.asp

CERT Advisory CA-2002-22, "Multiple Vulnerabilities in Microsoft SQL Server"
at: http://www.cert.org/advisories/CA-2002-22.html

CERT Vulnerability Note VU#484891, "Microsoft SQL Server 2000 contains stack
buffer overflow in SQL Server Resolution Service" at:
http://www.kb.cert.org/vuls/id/484891

NGSSoftware Insight Security Research Advisory #NISR03092002B, "Windows .NET
Server (RC1) and MSDE" at:
http://www.nextgenss.com/advisories/dotnet-msde.txt

Standards associated with this entry:
BID-5311: Microsoft SQL Server 2000 Resolution Service Stack Overflow
Vulnerability

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