Monday, July 30, 2018

Oracle Linux - security hardening - CIS control 1.1.1

As part of ensuring you deploy Oracle Linux 7 in a secure way the CIS benchmark van provide a good guidance. Following the CIS benchmark will ensure that most of the important security hardening topics will be considered. As with most general guidelines, the Oracle Linux 7 CIS benchmark, not all will apply on your specific situation. Having stated that, it is good to consider all the points mentioned in the benchmark and apply them with a comply or explain model.

Within this series of posts we will go through all the Oracle Linux 7 CIS benchmark controls and outline them a bit more than might have been done on the actual CIS benchmark.

control : Create Separate Partition for /tmp

The rational behind this control is : Since the /tmp directory is intended to be world-writable, there is a risk of resource exhaustion if it is not bound to a separate partition. In addition, making /tmp its own file system allows an administrator to set the noexec option on the mount, making /tmp useless for an attacker to install executable code. It would also prevent an attacker from establishing a hardlink to a system setuid program and wait for it to be updated. Once the program was updated, the hardlink would be broken and the attacker would have his own copy of the program. If the program happened to have a security vulnerability, the attacker could continue to exploit the known flaw.

What this in effect means is: that if an attacker would be able to flood /tmp with “junk” data it could lead to a situation where your system disks are full and the operating system is unable to function in the way it should. Additionally, as /tmp is a place most users will be able to write data to an attacker could also write scripts and code to it. As it provides a place to store code it can be abused from that point of view. If you allow users to write to the /tmp space however disallow them to execute code that is stored in /tmp this takes away this specific risk of code execution for code stored in /tmp.

The CIS benchmark provides the below standard code to verify if you have a separate /tmp in place:

grep "[[:space:]]/tmp[[:space:]]" /etc/fstab

Even though this check works the below might be a bit smarter and will provide a pass or fail result based upon the check:


grep "[[:space:]]/tmp[[:space:]]" /etc/fstab | wc -l&> /dev/null
if [ $? == 0 ]; then
   echo "fail"
   echo "pass"

In effect the above will do the same as the check promoted in the CIS benchmark document, however, it might be easier to include in a programmatic check. In case /tmp is not a separate file system it will return a fail on this control.

Tuesday, July 24, 2018

Oracle WebLogic - prevent users from bypassing the SAML authentication

The Oracle Critical Patch Update Advisory of July 2018 provides an advisory on patching Weblogic to resolve two SAML related security issues. Both issues have been registered as a CVE (Common Vulnerabilities and Exposures) entry. For more information you can refer to CVE-2018-2998 and CVE-2018-2933 who provide additional information as well as the Oracle website where you can find more information about the issues found and the way to mitigate against them.

At current the CVE database provides most insight on CVE-2018-2998:

Vulnerability in the Oracle WebLogic Server component of Oracle Fusion Middleware (subcomponent: SAML). Supported versions that are affected are,, and Easily exploitable vulnerability allows low privileged attacker with network access via HTTP to compromise Oracle WebLogic Server. Successful attacks of this vulnerability can result in unauthorized update, insert or delete access to some of Oracle WebLogic Server accessible data as well as unauthorized read access to a subset of Oracle WebLogic Server accessible data. CVSS 3.0 Base Score 5.4 (Confidentiality and Integrity impacts). CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N).

Both issues have been found by Denis Andzakovic from Pulse Security. Denis gives more insight on the Pulse Security website on the inner workings and additional details of the exact issue. In effect the issues results in the option to bypass the SAML authentication and by inserting an XML comment, an attacker can coerce the WebLogic SAML Service Provider to log in as another user. When an XML comment is added inside a NameID tag, the WebLogic server only processes the string after the comment. Adding the XML comment does not invalidate the SAML assertion’s signature.

Oracle has provided a solution for the issue found by Denis Andzakovic, the July CPU page provides additional information on how to patch your systems. As an addition the Oracle support website provides document 2421480.1 "Recommendations for Configuring Assertion Signatures in WebLogic Server" with additional information.

Monday, July 02, 2018

Oracle Linux - Caddy Server in OL7 Docker container

Today we pushed the first version of a Oracle Linux based Caddy server Docker image to the public Docker Hub. The Caddy webserver is seen as one of the most security minded webservers and is known to be not vulnerable for a large number CVEs. The main objective of the Caddy webserver is to provide a security first webserver.

For developers and DevOps teams who want to adopt Caddy Server, it is now available in a Oracle Linux 7 Docker Container on the OracleLinuxWorld docker hub page. You can pull the image with a:

docker pull oraclelinuxworld/ol7slim-caddyserver

The code for the Oracle Linux based Caddy Server container is available on the OracleLinuxWorld Github page. In case of any issues or requests; please raise a request on github.

When deploying your HTML code, the home directory for the Caddy server is /var/www/html where you can deploy all files you want to serve with Caddy.