[NEWS] IPRoute Fragmentation Denial of Service Vulnerability

From: support@securiteam.com
Date: 12/12/01


From: support@securiteam.com
To: list@securiteam.com
Date: Wed, 12 Dec 2001 16:29:44 +0100 (CET)

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  IPRoute Fragmentation Denial of Service Vulnerability
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SUMMARY

 <http://www.trunkmonkey.com/homenetwork/iproute/> IPRoute contains a
vulnerability that would allow a remote attacker to launch a DoS attack
against the product, thus blocking all access to and from the protected
network.

DETAILS

Affected software:
 * IPRoute version 1.18
 * IPRoute version 0.974
 * IPRoute version 0.973

IPRoute, by David F. Mischler, is PC-based router software for networks
running the Internet Protocol (IP). It can act as a dial on demand or
dedicated router between a LAN and a PPP, SLIP, Ethernet, wireless IP, or
cable modem link and allow transparent access from a LAN to the Internet
using a single IP address through Network Address Translation (NAT).
IPRoute can also act as a PPP server for dialup connections or route
between LANs.

The implementation of the router in IPRoute does not correctly handle tiny
fragmented packets, which split up the TCP header. If a series of tiny
fragmented packets were received by IPRoute, it would cause IPRoute to
fail. IPRoute could be put back into normal service by restarting the
interface, but all connections during the attack would drop. It is not
necessary for the attacker to establish a session through IPRoute in order
to exploit this vulnerability. ZapNET! firewalls are based on IPRoute and
may also be vulnerable.

The specific sequence of data packets involved with this vulnerability
cannot be generated as part of a legitimate connection.

Vulnerability reproduction:
Simply run "nmap -sS -f ip-address". IPRoute will be unable to send or
receive via the interface affected until it is manually restarted.

ADDITIONAL INFORMATION

The information has been provided by <mailto:maetrics@realwarp.net> Chris
Gragsone.

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