[squid-users] [squid-announce] [ADVISORY] SQUID-2019:5 Heap Overflow issue in HTTP Basic Authentication processing

[Amos Jeffries]

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    Squid Proxy Cache Security Update Advisory SQUID-2019:5
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Advisory ID:        SQUID-2019:5
Date:               July 12, 2019
Summary:            Heap Overflow issue
                    in HTTP Basic Authentication processing.
Affected versions:  Squid 4.0.23 -> 4.7
Fixed in version:   Squid 4.8
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    http://www.squid-cache.org/Advisories/SQUID-2019_5.txt
    http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-12527
__________________________________________________________________

Problem Description:

 Due to incorrect buffer management Squid is vulnerable to a
 heap overflow and possible remote code execution attack when
 processing HTTP Authentication credentials.

__________________________________________________________________

Severity:

 This allows a malicious client to write a substantial amount of
 arbitrary data to the heap. Potentially gaining ability to
 execute arbitrary code.

 On systems with memory access protections this can result in
 the Squid process being terminated unexpectedly. Resulting in a
 denial of service for all clients using the proxy.

 This issue is limited to traffic accessing the Squid Cache
 Manager reports or using the FTP protocol gateway.

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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-4-7f73e9c5d17664b882ed32590e6af310c247f320.patch>

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

__________________________________________________________________

Determining if your version is vulnerable:

 All Squid-2.x are not vulnerable.

 All Squid-3.x are not vulnerable.

 All Squid-4.x up to and including 4.0.22 are not vulnerable.

 All Squid-4.0.23 up to and including 4.7 built with Basic
 Authentication features are vulnerable.

__________________________________________________________________

Workarounds:

Either;

 Deny ftp:// protocol URLs being proxied and Cache Manager report
 access to all clients:

    acl FTP proto FTP
    http_access deny FTP
    http_access deny manager

Or,

 Build Squid with --disable-auth-basic

__________________________________________________________________

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 Jeriko One
 <jeriko.one at gmx.us>.

 Fixed by Amos Jeffries of Treehouse Networks Ltd.

__________________________________________________________________

Revision history:

 2019-05-14 14:56:49 UTC Initial Report
 2019-06-05 15:52:17 UTC CVE Assignment
 2019-06-19 05:58:36 UTC Patches Released
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END
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