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AUSCERT External Security Bulletin Redistribution
ESB-2001.423 -- FreeBSD-SA-01:61.squid
Squid in accelerator-only mode ignores ACLs
10 October 2001
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AusCERT Security Bulletin Summary
---------------------------------
Product: squid
Vendor: FreeBSD Ports Collection
Operating System: FreeBSD
BSD
Linux
Unix
Impact: Inappropriate Access
Access Required: Remote
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FreeBSD-SA-01:61 Security Advisory
FreeBSD, Inc.
Topic: Squid in accelerator-only mode ignores ACLs
Category: ports
Modules: squid22, squid23, squid24
Announced: 2001-10-08
Credits: Paul Nasrat <pnasrat@uk.now.com>
Affects: Ports collection prior to the correction date.
Corrected: 2001-07-29 12:29:00 (squid23)
2001-08-28 16:48:35 2001 UTC (squid24)
FreeBSD only: NO
I. Background
The Squid Internet Object Cache is a web proxy/cache.
II. Problem Description
If squid is configured in acceleration-only mode (http_accel_host is
set, but http_accel_with_proxy is off), then as a result of a bug,
access control lists (ACLs) are ignored.
III. Impact
A remote attacker may use the squid server in order to issue requests
to hosts that are otherwise inaccessible. Because the squid server
processes these requests as HTTP requests, the attacker cannot send or
retrieve arbitrary data. However, the attacker could use squid's
response to determine if a particular port is open on a victim host.
Therefore, the squid server may be used to conduct a port scan.
IV. Workaround
1) Do not run squid in acceleration-only mode.
2) Deinstall the squid port/package if you have it installed.
V. Solution
The port squid-2.3_1 and later 2.3 versions, and the port squid-2.4_5
and later 2.4 versions include fixes for this vulnerability. The
squid-2.3 and squid-2.2 ports have been deprecated and removed from
the ports collection, and users are advised to upgrade to squid-2.4 as
soon as possible.
1) Upgrade your entire ports collection and rebuild the squid port.
2) Deinstall the old package and install a new package dated after the
correction date, obtained from the following directories:
[i386]
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-4-stable/www/squid-2.3_1.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-4-stable/www/squid-2.4_5.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-5-current/www/squid-2.3_1.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-5-current/www/squid-2.4_5.tgz
[alpha]
Packages are not automatically generated for the alpha architecture at
this time due to lack of build resources.
3) Download a new port skeleton for the procmail port from:
http://www.freebsd.org/ports/
and use it to rebuild the port.
4) Use the portcheckout utility to automate option (3) above. The
portcheckout port is available in /usr/ports/devel/portcheckout or the
package can be obtained from:
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-4-stable/devel/portcheckout-2.0.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-5-current/devel/portcheckout-2.0.tgz
VI. Correction details
The following list contains the revision numbers of each file that was
corrected in the FreeBSD ports collection.
Affected port
Path Revision
- - -------------------------------------------------------------------------
squid22
*NOT CORRECTED*
squid23
ports/www/squid23/Makefile 1.78
ports/www/squid23/distinfo 1.57
squid24
ports/www/squid24/Makefile 1.84
ports/www/squid24/distinfo 1.61
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VII. References
<URL:http://www.squid-cache.org/bugs/show_bug.cgi?id=215>
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