A firewall problem?
jtrjtrjtr2001 at yahoo.com
Fri Jul 4 01:54:08 PDT 2003
Wont the following cause a firewall breach-
First we capture inbound packets to a firewall
assuming we have a man in the middle(M).
If (M) use block replay on packets he can inject bits
and pieces of his own information to an inbound
firewall and can go undetected?
M doesn't alter the source and destination ip's and is
perfectly acceptable to the firewall.Even a timestamp
won't work since a packet is expected at any time.
We can still re-calculate the CRC of Checksum field by
the same attack and replace the old crc/checksum after
changing various required bit positions.
Do firewall programs use initialisation vectors and a
chaning mode to prevent this attack?
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