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HTTP Proxy CONNECT Loop DoS?

Running a Nessus vulnerability scan on my network, it detects the IP of my Sophos UTM having one:

MEDIUM: HTTP Proxy CONNECT Loop DoS

Description

The proxy allows the users to perform repeated CONNECT requests to itself.

This allow anybody to saturate the proxy CPU, memory or file descriptors.

** Note that if the proxy limits the number of connections
** from a single IP (e.g. acl maxconn with Squid), it is
** protected against saturation and you may ignore this alert.

Solution

Reconfigure your proxy so that it refuses CONNECT requests to itself.

Port 8080 / tcp / http_proxy

Any ideas how I fix this?

Version 9.404-5

Thanks,

James.

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Parents

0 BAlfson over 8 years ago

James, have you selected 'Detect HTTP loopback' on the 'Misc' tab of 'Filtering Options'? Google site:community.sophos.com/products/unified-threat-management/f "Detect HTTP loopback" - Any luck with that?

Cheers - Bob

Sophos UTM Community Moderator
Sophos Certified Architect - UTM
Sophos Certified Engineer - XG
Gold Solution Partner since 2005

MediaSoft, Inc. USA
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0 jlbrown over 8 years ago in reply to BAlfson

Hi Bob.

Yes, 'Detect HTTP loopback' is on.

James.
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0 jlbrown over 8 years ago in reply to BAlfson

Hi Bob.

Yes, 'Detect HTTP loopback' is on.

James.
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0 BAlfson over 8 years ago in reply to jlbrown

Then I wonder if the Nessus scan didn't return a false-positive. Hopefully, former Astaro guru Jack Daniel will chime in. Jack now works for Tenable, but still appears here occasionally.

Cheers - Bob

Sophos UTM Community Moderator
Sophos Certified Architect - UTM
Sophos Certified Engineer - XG
Gold Solution Partner since 2005

MediaSoft, Inc. USA
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0 Jack Daniel over 8 years ago in reply to BAlfson

OK, I may be slow to respond, but eventually...

Since UTM scans are only "external" (non-credentialed), we have to make some assumptions based on responses. As Bob said, the loopback prevention setting should protect you- but give me another day or two to play in my lab and see what I find.

-jd
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0 Jack Daniel over 8 years ago in reply to Jack Daniel

I've been unable to duplicate this in my labs against a few versions of UTM.

If the problem continues, or returns, please reach out to me, This applies to any Nessus (or any other Tenable products) findings, I'm happy to bridge the Sophos and Tenable communities.

Cheers

-jd
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0 jlbrown over 8 years ago in reply to Jack Daniel

Hi Jack - Thanks for your investigations.

Just tried it again, and got the same vulnerability warning. This time with UTM 9.405-5, and Nessus 6.8.1.

Plugin Details

Severity: Medium
ID: 17154
Version: $Revision: 1.12 $
Type: remote
Family: Web Servers
Published: 2005/02/20
Modified: 2013/01/25

James.
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0 Jack Daniel over 8 years ago in reply to jlbrown

I'm running some more tests, if I can't duplicate the issue I may need to connect you with Tenable's support team to get to the bottom of it.

-jd
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0 Jack Daniel over 8 years ago in reply to jlbrown

Hi James, still unable to duplicate in my labs, please check DM and let's get this figured out.

-jd
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HTTP Proxy CONNECT Loop DoS?

Plugin Details