RHSA-2004:133 - Security Advisory

Topic

An updated squid package is avaliable that fixes a security vulnerability in
URL decoding and provides a new ACL type for protecting vulnerable clients.

Description

Squid is a full-featured Web proxy cache.

A bug was found in the processing of %-encoded characters in a URL in
versions of Squid 2.5.STABLE4 and earlier. If a Squid configuration uses
Access Control Lists (ACLs), a remote attacker could create URLs that would
not be correctly tested against Squid's ACLs, potentially allowing clients
to access prohibited URLs.

Users of Squid should update to these erratum packages which are not
vulnerable to this issue.

In addition, these packages contain a new Access Control type, "urllogin",
which can be used to protect vulnerable Microsoft Internet Explorer clients
from accessing URLs that contain login information. Such URLs are often
used by fraudsters to trick web users into revealing valuable personal data.

Note that the default Squid configuration does not make use of this new
access control type. You must explicitly configure Squid with ACLs that
use this new type, in accordance with your own site policies.

Solution

Before applying this update, make sure all previously released errata
relevant to your system have been applied.

To update all RPMs for your particular architecture, run:

rpm -Fvh [filenames]

where [filenames] is a list of the RPMs you wish to upgrade. Only those
RPMs which are currently installed will be updated. Those RPMs which are
not installed but included in the list will not be updated. Note that you
can also use wildcards (*.rpm) if your current directory *only* contains the
desired RPMs.

Please note that this update is also available via Red Hat Network. Many
people find this an easier way to apply updates. To use Red Hat Network,
launch the Red Hat Update Agent with the following command:

up2date

This will start an interactive process that will result in the appropriate
RPMs being upgraded on your system.

If up2date fails to connect to Red Hat Network due to SSL
Certificate Errors, you need to install a version of the
up2date client with an updated certificate. The latest version of
up2date is available from the Red Hat FTP site and may also be
downloaded directly from the RHN website:

https://rhn.redhat.com/help/latest-up2date.pxt

Affected Products

• Red Hat Enterprise Linux Server 3 x86_64
• Red Hat Enterprise Linux Server 3 ia64
• Red Hat Enterprise Linux Server 3 i386
• Red Hat Enterprise Linux Server 2 ia64
• Red Hat Enterprise Linux Server 2 i386
• Red Hat Enterprise Linux Workstation 3 x86_64
• Red Hat Enterprise Linux Workstation 3 ia64
• Red Hat Enterprise Linux Workstation 3 i386
• Red Hat Enterprise Linux Workstation 2 ia64
• Red Hat Enterprise Linux for IBM z Systems 3 s390x
• Red Hat Enterprise Linux for IBM z Systems 3 s390
• Red Hat Enterprise Linux for Power, big endian 3 ppc

Fixes

• BZ - 118032 - CAN-2004-0189 Squid ACL bypass

CVEs

• CVE-2004-0189

References

• http://www.squid-cache.org/Advisories/SQUID-2004_1.txt
• http://www.microsoft.com/security/incident/spoof.asp