portmap 4.0-8 DoS

Michal Zalewski (lcamtuf@BOSS.STASZIC.WAW.PL)
Wed, 01 Apr 1998 17:42:33 +0200

It's possible to perform DoS attack by sending small amount of junk to
tcp port 111 of machine running portmap 4.0 (and older). Simple exploit
follows (only to send a few random 8-bit chars):

telnet -E victim.com 111 </dev/random

It will affect specific operations/services on attacked host, like login -
depending on system speed, login attempt on idle machine (LA=0.01, Linux
2.0.x, x86) will take from over 10 seconds (k6/200MHz) to long minutes
(486dx/80MHz). During attack, many select() calls will fail (timeout),
so complex programs will become much slower (especially when resolving
domain names :), but LA will not change significally.

Smarter attacks (without /dev/random) are probably much more effective.

-- Nergal, nie obraziles sie chiba :?
_______________________________________________________________________
Michal Zalewski [lcamtuf@boss.staszic.waw.pl] <= finger for pub PGP key
Iterowac jest rzecza ludzka, wykonywac rekursywnie - boska [P. Deutsch]
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