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SQUID-2023:5 Denial of Service in FTP

High
yadij published GHSA-2g3c-pg7q-g59w Oct 21, 2023

Package

squid

Affected versions

5.0.3-5.9, 6.0-6.3

Patched versions

6.4

Description

Due to an Incorrect Conversion between Numeric Types
bug Squid is vulnerable to a Denial of Service
attack against FTP Native Relay input validation.

Due to an Incorrect Conversion between Numeric Types
bug Squid is vulnerable to a Denial of Service
attack against ftp:// URL validation and access control.


Severity:

This problem allows a remote client to perform Denial of Service
when sending ftp:// URLs in HTTP Request messages or constructing
ftp:// URLs from FTP Native input.

This issue is triggered during access control security checks,
meaning clients may not have been permitted to use the proxy yet.

FTP support is always enabled and cannot be disabled completely.

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_5.patch

Squid 6:

http://www.squid-cache.org/Versions/v6/SQUID-2023_5.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:

Squid older than 5.0.3 are not vulnerable.

All Squid-5.0.4 up to and including 5.6 are vulnerable.

All Squid-6.x up to and including 6.3 are vulnerable.


Workaround:

  • The FTP Native Relay input validation vector can be secured by
    removing all ftp_port directives from squid.conf.

  • There are no workarounds to avoid the ftp:// URL validation and
    access control vector.


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 The Measurement Factory.


Revision history:

2023-10-12 11:53:02 UTC Initial Report


END

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Changed
Confidentiality
None
Integrity
None
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

CVE ID

CVE-2023-46848

Weaknesses