[Full-disclosure] Exploring the UNKNOWN: Scanning the Internet via SNMP!
sub at room641a.net
Wed Mar 5 13:20:21 GMT 2008
That single UDP datagram is definitely faster. Compare the Code Red
worm to Sapphire (SQL Slammer), for instance:
"Previous scanning worms, such as Code Red, spread via many threads,
each invoking connect() to probe random addresses. Thus each thread's
scanning rate was limited by network latency, the time required to
transmit a TCP-SYN packet and wait for a response or timeout. In
principal, worms can compensate for this latency by invoking a
sufficiently large number of threads. However, in practice, context
switch overhead is significant and there are insufficient resources to
create enough threads to counteract the network delays -- the worm
quickly stalls and becomes latency limited.
In contrast, Sapphire's scanner was limited by each compromised
machine's bandwidth to the Internet. Since the SQL Server
vulnerability was exploitable using a single packet to UDP port 1434,
the worm was able to send these scans without requiring a response
from the potential victim."
(Oops, sorry for the copy to your inbox, Andrew.)
On 3/5/08, Andrew A <gluttony at gmail.com> wrote:
> hey dude, how is merely sending a single datagram not going to be faster
> than doing an entire handshake?
> On Tue, Mar 4, 2008 at 12:53 AM, Sebastian Krahmer <krahmer at suse.de> wrote:
> > This is not true. I doubt there is any measurable advantage
> > of UDP vs. TCP scans if you do it right.
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