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Squid Proxy Cache Security Update Advisory SQUID-2023:4
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Advisory ID: | SQUID-2023:4
Date: | November 2, 2023
Summary: | Denial of Service in SSL Certificate validation
Affected versions: | Squid 3.3 -> 3.5.28
| Squid 4.x -> 4.16
| Squid 5.x -> 5.9
| Squid 6.x -> 6.3
Fixed in version: | Squid 6.4
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Problem Description:
Due to an Improper Validation of Specified Index
bug Squid is vulnerable to a Denial of Service
attack against SSL Certificate validation.
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Severity:
This problem allows a remote server to perform Denial of
Service against Squid Proxy by initiating a TLS Handshake with
a specially crafted SSL Certificate in a server certificate
chain.
This attack is limited to HTTPS and SSL-Bump.
CVSS Score of 8.6
<https://nvd.nist.gov/vuln-metrics/cvss/v3-calculator?vector=AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H&version=3.1>
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Updated Packages:
This bug is fixed by Squid version 6.4.
In addition, patches addressing this problem for the stable
releases can be found in our patch archives:
Squid 5:
<http://www.squid-cache.org/Versions/v5/SQUID-2023_4.patch>
Squid 6:
<http://www.squid-cache.org/Versions/v6/SQUID-2023_4.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 Squid older than 3.3.0.1 are not vulnerable.
All Squid-3.3 up to and including 3.4.14 compiled without
--enable-ssl are not vulnerable.
All Squid-3.3 up to and including 3.4.14 compiled using
--enable-ssl are vulnerable.
All Squid-3.5 up to and including 3.5.28 compiled without
--with-openssl are not vulnerable.
All Squid-3.5 up to and including 3.5.28 compiled using
--with-openssl are vulnerable.
All Squid-4.x up to and including 4.16 compiled without
--with-openssl are not vulnerable.
All Squid-4.x up to and including 4.16 compiled using
--with-openssl are vulnerable.
Squid-5.x up to and including 5.9 compiled without
--with-openssl are not vulnerable.
All Squid-5.x up to and including 5.9 compiled using
--with-openssl are vulnerable.
All Squid-6.x up to and including 6.3 compiled without
--with-openssl are not vulnerable.
All Squid-6.x up to and including 6.3 compiled using
--with-openssl are vulnerable.
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Workaround:
Either,
Disable use of SSL-Bump features:
* Remove all ssl-bump options from http_port and https_port
* Remove all ssl_bump directives from squid.conf
Or,
Rebuild Squid using --without-openssl.
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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 you install and build Squid from the original Squid sources
then the <squid-users@xxxxxxxxxxxxxxxxxxxxx> 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
<https://bugs.squid-cache.org/>.
For reporting of security sensitive bugs send an email to the
<squid-bugs@xxxxxxxxxxxxxxxxxxxxx> 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.
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Credits:
This vulnerability was discovered by Joshua Rogers of Opera
Software.
Fixed by Andreas Weigel
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Revision history:
2023-10-12 11:53:02 UTC Initial Report
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END
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