2000103 : Smurf denial of service

Medium RiskMedium Risk

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Event description Jump to the top of this document

In a Smurf denial of service attack, ICMP echo request (ping) packets addressed to an IP broadcast address cause a large number of responses. When each host on the subnet replies to the same ping request, the large number of responses can consume all available network bandwidth, especially if data is appended to the ping request. This can prevent legitimate traffic from being transmitted during the attack. This attack is frequently used against third parties, where an attacker forges the target's source address in a Smurf attack against a different target. At the extreme, this attack can simultaneously disable both targets.

Windows systems do not respond to broadcast pings. However, this does not mean that all Microsoft networks are invulnerable to Smurf attacks.

Products that have this security check Jump to the top of this document

Smurf_Attack

This signature detects a possible Smurf amplifier attempt; an ICMP echo frame sent to a subnet address (x.x.x.0 or x.x.x.255). This may cause a flurry of echo responses, which can overwhelm the network or the systems involved. This is commonly known as the Smurf attack.

This signature replaces Smurf.

False Positive:A false positive can occur when the signature is triggered by people sending out broadcasts on the local segment. This is commonly seen by people inside corporate networks or on cable-modem segments. While this does not indicate an attempt to use your network as an Smurf amplifier, it does indicate that somebody is attempting discovery operations on your network.

Affected platforms Jump to the top of this document

How to remove this vulnerability Jump to the top of this document

Reconfigure your perimeter router or firewall to block ICMP echo requests on your internal network and block ICMP echo replies from entering your network. This will prevent someone from using your network to mount a SMURF attack against another target. It will also prevent an external attacker from targeting your hosts. However, neither of these actions will stop internal SMURF attacks.

References Jump to the top of this document

SANS Institute Resources Web site
Help Defeat Denial of Service Attacks: Step-by-Step
http://www.sans.org/dosstep/index.htm

CIAC Information Bulletin K-032
DDoS Mediation Action List
http://www.ciac.org/ciac/bulletins/k-032.shtml

CIAC Information Bulletin I-021a
"smurf" IP Denial-of-Service Attacks
http://www.ciac.org/ciac/bulletins/i-021a.shtml

FreeBSD Security Advisory FreeBSD-SA-98:06
smurf attack
ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/old/FreeBSD-SA-98:06.icmp.asc

Cisco Systems Technical Tips
"Smurfing": The Latest in Denial of Service Attacks
http://www.pentics.net/denial-of-service/presentations/

CERT Advisory CA-1998-01
smurf IP Denial-of-Service Attacks
http://www.cert.org/advisories/CA-1998-01.html

Pentics.net Web site
THE LATEST IN DENIAL OF SERVICE ATTACKS: "SMURFING"
http://www.pentics.net/denial-of-service/white-papers/smurf.cgi

Common Vulnerabilities and Exposures
ICMP messages to broadcast addresses are allowed, allowing for a Smurf attack that can cause a denial of service.
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-1999-0513

BugTraq
Multiple Vendor Smurf Denial of Service Vulnerability
http://www.securityfocus.com/bid/147

Information about this document Jump to the top of this document

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This page was created on Tue Feb 9 00:42:02 2010