By Joab Jackson
Sept 25, 2009
Abandon all hope, ye who get stung by a denial-of-service attacks.
Well, almost all hope. If the latest semiannual round of security
advisories from Cisco are any indication, DOS attacks continue to be a
serious -- and largely unsolvable -- problem for networks.
Earlier this week, Cisco issued nine advisories for its Internetwork
Operating System (IOS), the operating system software for most of the
company's routers and switches. The company also issued two advisories
for its Cisco Unified Communications Manager. The advisories came about
as part of the company's routine half-year patching cycle. In total, the
11 advisories cover 12 potential vulnerabilities.
Of the vulnerabilities Cisco issued, eight address vulnerabilities that
could have left customers open to denial-of-service attacks. In a DOS
attack, an attacker will flood a server or piece of networking equipment
with packets requesting a service of one sort or another. A distributed
denial of service (DDOS) consists of a flood of phony requests sent from
multiple computers, both as a way to avoid detection and to increase the
severity of the attack.
According to the advisories, attackers could down a Cisco router or
switch via a DOS attack by flooding them with H.323 multimedia
protocol-based packets, with Network Time Protocol packets, with Session
Initiation Protocol packets, or packets carrying requests in a number of
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