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Category:   Application (Generic)  >   Squid Vendors:   Squid-cache.org
(SCO Issues Fix) Squid Proxy Cache '%00' URL Character Access Control Bug May Let Remote Users Bypass Certain Access Controls
SecurityTracker Alert ID:  1011128
SecurityTracker URL:  http://securitytracker.com/id/1011128
CVE Reference:   CVE-2004-0189   (Links to External Site)
Date:  Sep 1 2004
Impact:   Host/resource access via network
Fix Available:  Yes  Vendor Confirmed:  Yes  
Version(s): Squid-2.x up to and including 2.5.STABLE4
Description:   A vulnerability was reported in the Squid Proxy Cache server in the processing of URLs containing '%00'. A remote user may be able to bypass certain access controls.

It is reported that a flaw in the '%xx' URL decoding function may allow a remote user to bypass access controls that use 'url_regex' access control list (ACL) types. The report indicates that Squid will insert a NUL character in place of '%00' in a URL before analyzing the URL for access control purposes. As a result, the 'http://foo%00@www.example.com/' URL will not be properly detected as a URL to be denied in accordance with the following type of access control configuration:

acl BadSite url_regex www\.example\.com
http_access deny BadSite

In this example, Squid will attempt to compare 'http://foo' with 'www\.example\.com' and will not find a match, so the URL will not be denied.

Mitch Adair is credited with reporting this flaw.

Impact:   A remote user may be able to submit a specially crafted URL to bypass url_regex access controls.
Solution:   SCO has issued a fix, described at:

ftp://ftp.sco.com/pub/updates/OpenServer/SCOSA-2004.13

Vendor URL:  www.squid-cache.org/Advisories/SQUID-2004_1.txt (Links to External Site)
Cause:   Access control error
Underlying OS:  Linux (Caldera/SCO)
Underlying OS Comments:  OpenServer 5.0.6, 5.0.7

Message History:   This archive entry is a follow-up to the message listed below.
Mar 1 2004 Squid Proxy Cache '%00' URL Character Access Control Bug May Let Remote Users Bypass Certain Access Controls



 Source Message Contents

Subject:  OpenServer 5.0.6 OpenServer 5.0.7 : squid %-encoded characters in a URL



-----BEGIN PGP SIGNED MESSAGE-----
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______________________________________________________________________________

			SCO Security Advisory

Subject:		OpenServer 5.0.6 OpenServer 5.0.7 : squid %-encoded characters in a URL
Advisory number: 	SCOSA-2004.13
Issue date: 		2004 August 31
Cross reference:	sr890342 fz529456 erg712609 CAN-2004-0189
______________________________________________________________________________


1. Problem Description

	The "%xx" URL decoding function in Squid 2.5STABLE4 and
	earlier allows remote attackers to bypass url_regex ACLs
	via a URL with a NULL ("%00") character, which causes Squid
	to use only a portion of the requested URL when comparing
	it against the access control lists. 

	The Common Vulnerabilities and Exposures project (cve.mitre.org) 
	has assigned the name CAN-2004-0189 to this issue.


2. Vulnerable Supported Versions

	System				Binaries
	----------------------------------------------------------------------
	OpenServer 5.0.6 		Squid distribution < 2.5.STABLE5
	OpenServer 5.0.7 		Squid distribution < 2.5.STABLE5

3. Solution

	The proper solution is to install the latest packages.

4. OpenServer 5.0.6

	4.1 First install oss646c or later

        4.2 Location of oss646c

        ftp://ftp.sco.com/pub/openserver5/oss646c/

        4.3 Verification of oss646c

        MD5 (VOL.000.000) = f19b6c6949f615316bfb075d249989e8
        MD5 (VOL.000.001) = 341ff8553aecd2c7b0c2beaf83030d0f
        MD5 (VOL.000.002) = 6e46708ad8029e12280d4f9ac60ab814
        MD5 (VOL.000.003) = 2868b64a6a6db742adb3b485be645d7e
        MD5 (VOL.000.004) = 1696fe1db9bb063827ee5e76e58dff84
        MD5 (VOL.000.005) = f39da342f8af72fcaccdf478dca04109
        MD5 (VOL.000.006) = 2b31611c8af7d2e7910d6e8e3cf701a6
        MD5 (VOL.000.007) = d0175c0f4e3ed29435b1eab95609f8f4
        MD5 (VOL.000.008) = aa9e8a525c341fed077f981b1dacb486
        MD5 (VOL.000.009) = 8e023af67b57507824406bdda322079a
        MD5 (VOL.000.010) = 2b46e8adba8ae0b64109f2069da978a2

	4.4 Installation of oss646c

	See ftp://ftp.sco.com/pub/openserver5/oss646c/oss646c.txt

	4.5 Next install xorg-6.7.0Ba or later

	4.6 Location of xorg-6.7.0Ba

	ftp://ftp.sco.com/pub/openserver5/opensrc/xorg-6.7.0Ba/

	4.7 Verification of xorg-6.7.0Ba

	MD5 (VOL.000.000) = 289d1070c4135e4d25a20501dbca08d8
	MD5 (VOL.000.001) = 4111dadf961d4ef88e89112070f3e811
	MD5 (VOL.000.002) = 4c4cdf4bf4c28045b7b323cfa407829f
	MD5 (VOL.000.003) = d7e8da318d1c4df6fff14f60d993cf45
	MD5 (VOL.000.004) = bfc0571f1fededd1780fafa76db9be90

	4.8 Installation of xorg-6.7.0Ba

	See ftp://ftp.sco.com/pub/openserver5/opensrc/xorg-6.7.0Ba/xorg67_rn.txt

	4.9 Next install gwxlibs-1.3.3Db or later

	4.10 Location of gwxlibs-1.3.3Db

	ftp://ftp.sco.com/pub/updates/OpenServer/SCOSA-2004.10

        4.11 Verification

        MD5 (VOL.000.000) = a85cf35c417903522392064aaa98f0a4
        MD5 (VOL.000.001) = d4383d6bc74bb6e873e7a4c8dfdc4e6b
        MD5 (VOL.000.002) = c5657b1358ef96177ae15fdcfec7132f
        MD5 (VOL.000.003) = 4c88ceb3502330b4c4d5e07ca7fc5214

	4.12 Installation of gwxlibs-1.3.3Db

	See ftp://ftp.sco.com/pub/updates/OpenServer/SCOSA-2004.10/SCOSA-2004.10.txt

	4.13 Next install perl-5.8.4Aa or later

	4.14 Location of perl-5.8.4Aa

	ftp://ftp.sco.com/pub/openserver5/opensrc/perl-5.8.4Aa/

	4.15 Verification

	MD5 (VOL.000.000) = b83b5e0ae513a1cb206baf37c4741653
	MD5 (VOL.000.001) = 1ab35276079e7661e38b72047cec488a
	MD5 (VOL.000.002) = 64a76371eae54e95d0b7e99be25f0a8a
	MD5 (VOL.000.003) = 724521beddc740ae4958fd63d1c45f3f
	MD5 (VOL.000.004) = f1d631477f16ce7b9512fbe60d9e3d0e

	4.16 Installation of perl-5.8.4Aa

	See ftp://ftp.sco.com/pub/openserver5/opensrc/perl-5.8.4Aa/perl584_rn.txt

	4.17 Location of Squid Fixed Binaries

	ftp://ftp.sco.com/pub/updates/OpenServer/SCOSA-2004.13

	4.18 Verification

	MD5 (VOL.000.000) = 656d0097b861d9e2375f672579e15c6b
	MD5 (VOL.000.001) = 4f15cb68083fb6ceff3dd3c72aed41a2
	MD5 (VOL.000.002) = 6fbf1b23e9d86f621de916bca4e476b3
	MD5 (VOL.000.003) = fefcfc2f2d4f56e8be34d917a882bd41

	md5 is available for download from
		ftp://ftp.sco.com/pub/security/tools

	4.19 Installing Fixed Binaries

	Upgrade the affected binaries with the following sequence:

	1) Download the VOL* files to a directory.

	2) Run the custom command, specify an install from media
	images, and specify the directory as the location of
	the images.


5. OpenServer 5.0.7

	5.1 Location of Fixed Binaries

	Supplement CD 3

	http://www.sco.com/support/update/download/osr507list.html

	5.2 Verification

	MD5 (osr507suppcd3.iso) = 129229594bd3a020db429e7de8b95def

	md5 is available for download from
		ftp://ftp.sco.com/pub/security/tools

	5.3 Installing Fixed Binaries

	See the Supplement CD 3 Release Notes

	ftp://ftp.sco.com/pub/openserver5/507/iso/suppcd3/osr507suppcd3.txt

6. References

	Specific references for this advisory:
		http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2004-0189 
		http://xforce.iss.net/xforce/xfdb/15366

	SCO security resources:
		http://www.sco.com/support/security/index.html

	SCO security advisories via email
		http://www.sco.com/support/forums/security.html

	This security fix closes SCO incidents sr890342 fz529456
	erg712609.


7. Disclaimer

	SCO is not responsible for the misuse of any of the information
	we provide on this website and/or through our security
	advisories. Our advisories are a service to our customers
	intended to promote secure installation and use of SCO
	products.

______________________________________________________________________________

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