attack
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... filters; these filters are used for
keeping attackers from accessing private systems and information,
while permitting friendly agents to transfer data between private
...
... network
equipment vendors to anticipate possible attacks against their
equipment and to implement robust mechanisms to deflect such attacks.
...
... equipment vendors to anticipate possible attacks against their
equipment and to implement robust mechanisms to deflect such attacks.
The growth of the global Internet ...
... "undesirable elements" manifested in antisocial behavior. Recent
months have seen the use of novel attacks on Internet hosts, which
...
... have in some cases led to the compromise of sensitive data.
Increasingly sophisticated attackers have begun to exploit the more
subtle aspects of the Internet Protocol; fragmentation ...
... small as to be impractical because of data and computational
overhead. Attackers can sometimes exploit typical filter behavior
and the ability to create ...
... Tiny Fragment Attack ...
... Example of the Tiny Fragment Attack ...
... Prevention of the Tiny Fragment Attack ...
...
In a router, one can prevent this sort of attack by enforcing
certain limits on fragments passing through, namely, that the
...
... TCP packets are vulnerable to tiny-fragment attacks and the
test need not be applied to IP packets carrying other transport
protocols ...
... fragments below,
however, this test does not block all fragmentation attacks,
and is in fact unnecessary when a more general technique is
used.
...
... Overlapping Fragment Attack ...
... fragments.
Given such a reassembly implementation, an attacker could construct a
series of packets in which the lowest (zero-offset) fragment would
...
... IP implementations are not guaranteed to be
immune to overlapping-fragment attacks. The 4.3 BSD reassembly
implementation takes care to avoid these attacks by forcing data from
...
... fragment attacks. The 4.3 BSD reassembly
implementation takes care to avoid these attacks by forcing data from
lower-offset fragments to take precedence over data from higher-
...
... Example of the Overlapping Fragment Attack ...
... Prevention of the Overlapping Fragment Attack ...
... vulnerability of hosts to this
attack is quite large.
By adopting a better strategy in a router ...
... FO==1 fragments also protects against the
tiny fragment attack, as discussed earlier.
RFC 791std5 ...
... algorithm, then, for ensuring that filters work in the
face of both the tiny fragment attack and the overlapping fragment
attack is:
...
... filters work in the
face of both the tiny fragment attack and the overlapping fragment
attack is:
IF FO ...