From: Kevin (kkadowgmail.com)
Date: Thu Jun 29 2006 - 12:49:22 CDT

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On 6/29/06, Terminal Entry <Securitypeadro.net> wrote:
> When the malicious code writers build their viruses and Trojans why not code
> the threats to detect the use of proxy servers and if used, connect through
> them.

One reason why not is that it's easier to aim for the largest
population of easy targets, which will always be the home consumer.

There are other optimizations a worm or trojan author would choose
when targeting code to a corporate environment; so far I haven't
seen malware optimized for intranet deployment :)

> Working in Corporate America, most firewall configurations block
> outbound TCP 80, as the proxies listen on other non-standard TCP ports.

You'd think that, but when I talk to vendors about "proxy aware" support
in their custom applications, they seem genuinely surprised that
any corporation mandates HTTP traffic to go only via proxy.

> A virus should first check to determine if a proxy is used and if so use that
> proxy to download the malicious code, backdoor, etc.

There are already a few worms/trojans using the MSIE API instead of
carrying their own http client library. Call the API appropriately,
and you'll use a proxy as needed, without any extra work/code.

Same goes for using Outlook instead of an integrated SMTP engine.

One tricky part, many proxy gateways require authentication,
in some cases the credentials will not (or can not) be cached.

Kevin

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