DLA 3293-1: modsecurity-crs security update
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Debian LTS Advisory DLA-3293-1 debian-lts@lists.debian.org
https://www.debian.org/lts/security/ Tobias Frost
January 30, 2023 https://wiki.debian.org/LTS
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Package : modsecurity-crs
Version : 3.2.3-0+deb10u3
CVE ID : CVE-2018-16384 CVE-2020-22669 CVE-2021-35368 CVE-2022-39955
CVE-2022-39956 CVE-2022-39957 CVE-2022-39958
Debian Bug : 924352 992000 1021137
Multiple issues were found in modsecurity-crs, a set of generic attack
detection rules for use with ModSecurity or compatible web application
firewalls, which allows remote attackers to bypass the web applications
firewall.
If you are using modsecurity-crs with apache2 / libapache2-modsecurity, please
make sure to review your modsecurity configuration, usually
/etc/modsecurity/modsecurity.conf, against the updated recommended
configration, available in /etc/modsecurity/modsecurity.conf-recommended:
Some of the changes to the recommended rules are required to avoid WAF bypasses
in certain circumstances.
Please note that CVE-2022-39956 requires an updated modsecurity-apache packge,
which has been previously uploaded to buster-security, see Debian LTS Advisory
DLA-3283-1 for details.
If you are using some other solution in connection with the
modsecurity-ruleset, for example one that it is using libmodsecurity3, your
solution might error out with an error message like "Error creating rule:
Unknown variable: MULTIPART_PART_HEADERS". In this case you can disable the
mitigation for CVE-2022-29956 by removing the rule file
REQUEST-922-MULTIPART-ATTACK.conf. However, be aware that this will disable
the protection and could allow attackers to bypass your Web Application
Firewall.
There is no package in Debian which depends on libmodsecurity3, so if you are
only using software which is available from Debian, you are not affected by
this limitation.
Kudos to @airween for the support and help while perparing the update.
CVE-2018-16384
A SQL injection bypass (aka PL1 bypass) exists in OWASP ModSecurity Core Rule
Set (owasp-modsecurity-crs) through v3.1.0-rc3 via {`a`b} where a is a special
function name (such as "if") and b is the SQL statement to be executed.
CVE-2020-22669
Modsecurity owasp-modsecurity-crs 3.2.0 (Paranoia level at PL1) has a SQL
injection bypass vulnerability. Attackers can use the comment characters and
variable assignments in the SQL syntax to bypass Modsecurity WAF protection and
implement SQL injection attacks on Web applications.
CVE-2022-39955
The OWASP ModSecurity Core Rule Set (CRS) is affected by a partial rule set
bypass by submitting a specially crafted HTTP Content-Type header field that
indicates multiple character encoding schemes. A vulnerable back-end can
potentially be exploited by declaring multiple Content-Type "charset" names and
therefore bypassing the configurable CRS Content-Type header "charset" allow
list. An encoded payload can bypass CRS detection this way and may then be
decoded by the backend. The legacy CRS versions 3.0.x and 3.1.x are affected,
as well as the currently supported versions 3.2.1 and 3.3.2. Integrators and
users are advised to upgrade to 3.2.2 and 3.3.3 respectively.
CVE-2022-39956
The OWASP ModSecurity Core Rule Set (CRS) is affected by a partial rule set
bypass for HTTP multipart requests by submitting a payload that uses a
character encoding scheme via the Content-Type or the deprecated
Content-Transfer-Encoding multipart MIME header fields that will not be decoded
and inspected by the web application firewall engine and the rule set. The
multipart payload will therefore bypass detection. A vulnerable backend that
supports these encoding schemes can potentially be exploited. The legacy CRS
versions 3.0.x and 3.1.x are affected, as well as the currently supported
versions 3.2.1 and 3.3.2. Integrators and users are advised upgrade to 3.2.2
and 3.3.3 respectively. The mitigation against these vulnerabilities depends on
the installation of the latest ModSecurity version (v2.9.6 / v3.0.8).
CVE-2022-39957
The OWASP ModSecurity Core Rule Set (CRS) is affected by a response body
bypass. A client can issue an HTTP Accept header field containing an optional
"charset" parameter in order to receive the response in an encoded form.
Depending on the "charset", this response can not be decoded by the web
application firewall. A restricted resource, access to which would ordinarily
be detected, may therefore bypass detection. The legacy CRS versions 3.0.x and
3.1.x are affected, as well as the currently supported versions 3.2.1 and
3.3.2. Integrators and users are advised to upgrade to 3.2.2 and 3.3.3
respectively.
CVE-2022-39958
The OWASP ModSecurity Core Rule Set (CRS) is affected by a response body bypass
to sequentially exfiltrate small and undetectable sections of data by
repeatedly submitting an HTTP Range header field with a small byte range. A
restricted resource, access to which would ordinarily be detected, may be
exfiltrated from the backend, despite being protected by a web application
firewall that uses CRS. Short subsections of a restricted resource may bypass
pattern matching techniques and allow undetected access. The legacy CRS
versions 3.0.x and 3.1.x are affected, as well as the currently supported
versions 3.2.1 and 3.3.2. Integrators and users are advised to upgrade to 3.2.2
and 3.3.3 respectively and to configure a CRS paranoia level of 3 or higher.
For Debian 10 buster, these problems have been fixed in version
3.2.3-0+deb10u3.
We recommend that you upgrade your modsecurity-crs packages.
For the detailed security status of modsecurity-crs please refer to
its security tracker page at:
https://security-tracker.debian.org/tracker/modsecurity-crs
Further information about Debian LTS security advisories, how to apply
these updates to your system and frequently asked questions can be
found at: https://wiki.debian.org/LTS
A modsecurity-crs security update has been released for Debian GNU/Linux 10 LTS to address multiple issues.
