Proxy vulnerability in TrendMicro InterScan-VirusWall V3.6

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Greetings!

A quite well known (i.e. ancient) type of proxy vulnerability was
found for TrendMicro's InterScan VirusWall V3.6 This general problem
has been known to be an issue with plain HTTP proxies like the Squid
for ages (e.g. http://www.squid-cache.org/Doc/FAQ/FAQ-10.html#ss10.14).

The vulnerability can be exploited using the CONNECT method to
connect to a different server, e.g. an internal mailserver as
port usage is completely unrestricted by the ISVW proxies V 3.6

Example:
you = 6.6.6.666
Trendmicro ISVW = 1.1.1.1 (http proxy at port 80)
Internal Mailserver = 2.2.2.2

    connect with "telnet 1.1.1.1 80" to ISVW proxy and enter
    CONNECT 2.2.2.2:25 / HTTP/1.0

    response: mail server banner - and running SMTP session e.g.
    to send SPAM from.

You can connect to any TCP port on any machine the proxy
can connect to. Telnet, SMTP, POP, etc.

Solution:
Update to ISVW 3.7 Build 1190 or newer (available since some
weeks now).

temp. Workarounds:
- disable the HTTP proxy (safe but inconvenient)
- You have a firewall that prevents unauthorized access to the
Trend ISVW proxy, don't you?

Volker Tanger
IT-Security Consulting

discon gmbh
Wrangelstraße 100
D-10997 Berlin

fon +49 30 6104-3307
fax +49 30 6104-3461

[email protected]
http://www.discon.de/

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