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Gentoo Linux Security Advisory GLSA 200403-11 |
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http://security.gentoo.org |
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Severity: Normal |
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Title: Squid ACL [url_regex] bypass vulnerability |
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Date: March 30, 2004 |
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Bugs: #45273 |
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ID: 200403-11 |
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Synopsis |
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======== |
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|
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Squid versions 2.0 through to 2.5.STABLE4 could allow a remote attacker |
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to bypass Access Control Lists by sending a specially-crafted URL |
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request containing '%00': in such circumstances; the url_regex ACL may |
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not properly detect the malicious URL, allowing the attacker to |
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effectively bypass the ACL. |
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|
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Background |
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========== |
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|
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Squid is a fully-featured Web Proxy Cache designed to run on Unix |
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systems that supports proxying and caching of HTTP, FTP, and other |
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URLs, as well as SSL support, cache hierarchies, transparent caching, |
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access control lists and many other features. |
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|
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Affected packages |
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================= |
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|
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------------------------------------------------------------------- |
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Package / Vulnerable / Unaffected |
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------------------------------------------------------------------- |
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net-www/squid < 2.5.5 >= 2.5.5 |
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|
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Description |
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=========== |
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|
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A bug in Squid allows users to bypass certain access controls by |
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passing a URL containing "%00" which exploits the Squid decoding |
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function. This may insert a NUL character into decoded URLs, which may |
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allow users to bypass url_regex access control lists that are enforced |
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upon them. |
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In such a scenario, Squid will insert a NUL character after the"%00" |
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and it will make a comparison between the URL to the end of the NUL |
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character rather than the contents after it: the comparison does not |
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result in a match, and the user's request is not denied. |
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Impact |
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====== |
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|
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Restricted users may be able to bypass url_regex access control lists |
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that are enforced upon them which may cause unwanted network traffic as |
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well as a route for other possible exploits. Users of Squid 2.5STABLE4 |
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and below who require the url_regex features are recommended to upgrade |
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to 2.5STABLE5 to maintain the security of their infrastructure. |
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Workaround |
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========== |
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A workaround is not currently known for this issue. All users are |
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advised to upgrade to the latest version of Squid. |
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Resolution |
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========== |
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Squid can be updated as follows: |
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# emerge sync |
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# emerge -pv ">=net-www/squid-2.5.5" |
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# emerge ">=net-www/squid-2.5.5" |
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|
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References |
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========== |
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|
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[ 1 ] http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2004-0189 |
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[ 2 ] http://www.squid-cache.org/Advisories/SQUID-2004_1.txt |
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Concerns? |
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========= |
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Security is a primary focus of Gentoo Linux and ensuring the |
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confidentiality and security of our users machines is of utmost |
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importance to us. Any security concerns should be addressed to |
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security@g.o or alternatively, you may file a bug at |
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http://bugs.gentoo.org. |
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