Headline
CVE-2023-46724: SQUID-2023:4 Denial of Service in SSL Certificate validation
Squid is a caching proxy for the Web. Due to an Improper Validation of Specified Index bug, Squid versions 3.3.0.1 through 5.9 and 6.0 prior to 6.4 compiled using --with-openssl are vulnerable to a Denial of Service attack against SSL Certificate validation. 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. This bug is fixed in Squid version 6.4. In addition, patches addressing this problem for the stable releases can be found in Squid’s patch archives. Those who you use a prepackaged version of Squid should refer to the package vendor for availability information on updated packages.
Due to an Improper Validation of Specified Index
bug Squid is vulnerable to a Denial of Service
attack against SSL Certificate validation.
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
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.
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.
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.
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 [email protected] 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
[email protected] 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 Joshua Rogers of Opera
Software.
Fixed by Andreas Weigel
Revision history:
2023-10-12 11:53:02 UTC Initial Report
END
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