Amazon Linux AMI : tomcat7 (ALAS-2020-1352)

critical Nessus Plugin ID 134574

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Synopsis

The remote Amazon Linux AMI host is missing a security update.

Description

In Apache Tomcat 9.0.0.M1 to 9.0.30, 8.5.0 to 8.5.50 and 7.0.0 to 7.0.99 the HTTP header parsing code used an approach to end-of-line parsing that allowed some invalid HTTP headers to be parsed as valid.
This led to a possibility of HTTP Request Smuggling if Tomcat was located behind a reverse proxy that incorrectly handled the invalid Transfer-Encoding header in a particular manner. Such a reverse proxy is considered unlikely. (CVE-2020-1935)

The refactoring present in Apache Tomcat 9.0.28 to 9.0.30, 8.5.48 to 8.5.50 and 7.0.98 to 7.0.99 introduced a regression. The result of the regression was that invalid Transfer-Encoding headers were incorrectly processed leading to a possibility of HTTP Request Smuggling if Tomcat was located behind a reverse proxy that incorrectly handled the invalid Transfer-Encoding header in a particular manner. Such a reverse proxy is considered unlikely. (CVE-2019-17569)

When using the Apache JServ Protocol (AJP), care must be taken when trusting incoming connections to Apache Tomcat. Tomcat treats AJP connections as having higher trust than, for example, a similar HTTP connection. If such connections are available to an attacker, they can be exploited in ways that may be surprising. In Apache Tomcat 9.0.0.M1 to 9.0.0.30, 8.5.0 to 8.5.50 and 7.0.0 to 7.0.99, Tomcat shipped with an AJP Connector enabled by default that listened on all configured IP addresses. It was expected (and recommended in the security guide) that this Connector would be disabled if not required. This vulnerability report identified a mechanism that allowed: - returning arbitrary files from anywhere in the web application - processing any file in the web application as a JSP Further, if the web application allowed file upload and stored those files within the web application (or the attacker was able to control the content of the web application by some other means) then this, along with the ability to process a file as a JSP, made remote code execution possible. It is important to note that mitigation is only required if an AJP port is accessible to untrusted users. Users wishing to take a defence-in-depth approach and block the vector that permits returning arbitrary files and execution as JSP may upgrade to Apache Tomcat 9.0.31, 8.5.51 or 7.0.100 or later. A number of changes were made to the default AJP Connector configuration in 9.0.31 to harden the default configuration. It is likely that users upgrading to 9.0.31, 8.5.51 or 7.0.100 or later will need to make small changes to their configurations. (CVE-2020-1938)

As part of our fix for this CVE, we are disabling Tomcat 2019 AJP connector in the default configuration in alignment with the upstream changes. This change will require customers who use the default Tomcat configuration (in which the AJP connector was previously enabled) to explicitly re-enable the connector if they need it. Also take note that a connector configured without an explicit address will only bind to the loopback address.

Examples of output from netstat before and after updating tomcat8 and tomcat7 are below (note that it is the same on AL1 and AL2 with both tomcat7 and tomcat8).

AL1 tomcat7 :

before :

tcp6 0 0 :::8009 :::* LISTEN 25772/java

tcp6 0 0 :::8080 :::* LISTEN 25772/java

tcp6 0 0 127.0.0.1:8005 :::* LISTEN 25772/java

After :

tcp6 0 0 :::8080 :::* LISTEN 25772/java

tcp6 0 0 127.0.0.1:8005 :::* LISTEN 25772/java

To re-enable the AJP port in Tomcat for AL1, users can uncomment the following line in /etc/tomcat{TOMCAT_VERSION}/server.xml and restart the service :



See also :

Apache Tomcat release notes

Tomcat 7

<a href='http://tomcat.apache.org/security-8.html#Fixed_in_Apache_Tomcat_ 8.5.51'>Tomcat 8

RedHat <a href='https://access.redhat.com/solutions/4851251'>solutions

Solution

Run 'yum update tomcat7' to update your system.

Plugin Details

Severity: Critical

ID: 134574

File Name: ala_ALAS-2020-1352.nasl

Version: 1.6

Type: local

Agent: unix

Family: Amazon Linux Local Security Checks

Published: 3/16/2020

Updated: 1/11/2023

Supported Sensors: Agentless Assessment, Continuous Assessment, Frictionless Assessment Agent, Frictionless Assessment AWS, Nessus Agent, Nessus

Risk Information

VPR

Risk Factor: Critical

Score: 9.0

CVSS v2

Risk Factor: High

Base Score: 7.5

Temporal Score: 6.5

Vector: CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:P

CVSS Score Source: CVE-2020-1938

CVSS v3

Risk Factor: Critical

Base Score: 9.8

Temporal Score: 9.4

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Temporal Vector: CVSS:3.0/E:H/RL:O/RC:C

Vulnerability Information

CPE: p-cpe:/a:amazon:linux:tomcat7-admin-webapps, p-cpe:/a:amazon:linux:tomcat7-javadoc, p-cpe:/a:amazon:linux:tomcat7-docs-webapp, p-cpe:/a:amazon:linux:tomcat7-jsp-2.2-api, p-cpe:/a:amazon:linux:tomcat7-servlet-3.0-api, p-cpe:/a:amazon:linux:tomcat7, p-cpe:/a:amazon:linux:tomcat7-log4j, p-cpe:/a:amazon:linux:tomcat7-lib, p-cpe:/a:amazon:linux:tomcat7-webapps, p-cpe:/a:amazon:linux:tomcat7-el-2.2-api, cpe:/o:amazon:linux

Required KB Items: Host/local_checks_enabled, Host/AmazonLinux/release, Host/AmazonLinux/rpm-list

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 3/13/2020

Vulnerability Publication Date: 2/24/2020

CISA Known Exploited Vulnerability Due Dates: 3/17/2022

Reference Information

CVE: CVE-2019-17569, CVE-2020-1935, CVE-2020-1938

ALAS: 2020-1352

Detections

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