[squid-users] [squid-announce] [ADVISORY] SQUID-2019:1 Denial of Service issue in cachemgr.cgi

[Amos Jeffries]

__________________________________________________________________

    Squid Proxy Cache Security Update Advisory SQUID-2019:1
__________________________________________________________________

Advisory ID:        SQUID-2019:1
Date:               July 12, 2019
Summary:            Denial of Service issue
                    in cachemgr.cgi
Affected versions:  Squid 4.x -> 4.7
Fixed in version:   Squid 4.8
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    http://www.squid-cache.org/Advisories/SQUID-2019_1.txt
    http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-12854
__________________________________________________________________

Problem Description:

 Due to incorrect string termination the cachemgr.cgi may access
 unallocated memory.

 On systems with memory access protections this can result in
 the CGI process terminating unexpectedly. Resulting in a
 denial of service for all clients using it.

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Severity:

 This problem allows a remote attacker with access to the Squid
 manager API to perform a denial of service on other clients.

 This problem is limited to the cachemgr CGI binary.

 Web servers which run per-client instances of CGI tools are
 affected by the issue, but the denial of service is not able to
 affect other clients.

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Updated Packages:

 This bug is fixed by Squid version 4.8.

 In addition, patches addressing this problem for the stable
 releases can be found in our patch archives:

Squid 4:
 http://www.squid-cache.org/Versions/v4/changesets/squid-4-2981a957716c61ff7e21eee1d7d6eb5a237e466d.patch

 If you are using a prepackaged version of Squid then please refer
 to the package vendor for availability information on updated
 packages.

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Determining if your version is vulnerable:

 All cachemgr.cgi 3.x and older versions are not vulnerable.

 All cachemgr.cgi 4.x versions up to and including 4.7 are
 vulnerable.

 All Squid-4.7 and older versions accessed via the http:// URL
 manager interface are not vulnerable.

To determine the version and interface, look at the footer of
manager reports for the "Generated by" string.

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Workarounds:

Either;

 Convert to exclusively using the HTTP manager interface until
 cachemgr.cgi can be upgraded to a fixed build.

Or;

 Deny all access with 'manager' ACL in squid.conf.

 This completely removes the vulnerability at cost of reduced
 management and monitoring capabilities.

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Contact details for the Squid project:

 For installation / upgrade support on binary packaged versions
 of Squid: Your first point of contact should be your binary
 package vendor.

 If your install and build Squid from the original Squid sources
 then the squid-users at lists.squid-cache.org mailing list is your
 primary support point. For subscription details see
 <http://www.squid-cache.org/Support/mailing-lists.html>.

 For reporting of non-security bugs in the latest STABLE release
 the squid bugzilla database should be used
 <http://bugs.squid-cache.org/>.

 For reporting of security sensitive bugs send an email to the
 squid-bugs at lists.squid-cache.org mailing list. It's a closed
 list (though anyone can post) and security related bug reports
 are treated in confidence until the impact has been established.

__________________________________________________________________

Credits:

 This vulnerability was discovered by Alex Rousskov of The
 Measurement Factory.

 Fixed by Amos Jeffries from Treehouse Networks Ltd.

__________________________________________________________________

Revision history:

 2019-04-10 21:13:50 UTC Initial Report
 2019-05-18 09:43:41 UTC Patch Released
 2019-06-16 10:52:51 UTC CVE Assignment
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END
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