For a new project I had to foresee an SMTP relay server that supported client authentication. I love the simplicity of Postfix but setting it up with client authentication required more than just ‘a push of a button’. Below are some -unstructured- notes on how to achieve this.
The client authentication in Postfix is handled by Cyrus SASL. The Simple Authentication and Security Layer or SASL is a specification that describes how authentication mechanisms can … Read more.
The Elastic stack is a great tool to quickly visualise large volumes of log files. In a previous post I described how to load stored Windows EVTX logs in Security Onion, with the help of Winlogbeat. In this new post I describe something similar with the goal to analyse Linux auditd logs with Elastic. Instead of using the Elastic stack of Security Onion I use an Elastic cluster via Docker and instead of storing the … Read more.
I recently bought a Philips Hue light system. It allows you to control your lights via a smartphone app and set the right colour mood. Setup is easy, you connect a light bridge to your home router, connect with the app and then setup the lights. The system also includes an API to build your own apps.
In 2015 I tweeted on an episode of CSI Cyber where “good” code automagically turned green whereas “bad” … Read more.
I use a couple of Ubuntu Linux virtual machines via VMWare Fusion (OSX) for security testing. Some of the security tools have a web interface. Because I want to test with different environment setups I have /var/www/ mounted via Shared Folders on the host OSX. This has as advantage that
Files are stored centrally (on the host OS) Different environments can use the same files and configuration (if stored in /var/www) I can use native … Read more.
One of my virtual machines hosted at Gandi had an excessive amount of error messages
The cause of this error message are the IPv6 router announcements that try to discover and configure the IPv6 neighbourhood. The excessive amount of messages were polluting the logs.
After contacting the Gandi helpdesk they provided insight on the cause of the error message and provided mitigations to prevent these type of errors. I had to update /etc/sysctl.conf with … Read more.
One of the recent incidents I had to handle involved a compromised webhost. This allowed me to do some Exploring webshells on a WordPress site. In the aftermath of the investigation I searched for tools that could have improved my tasks (evaluating which files might have been compromised).
One of the approaches I had in mind was take a hash of every file and then verify that hash with Virustotal. This would have worked in … Read more.
I recently had to handle a case where a website development company was hacked. This post describes some of my findings during the investigation.
All of the company websites were hosted on one virtual server running Linux. Most of these websites were WordPress powered. The management of the server was done via DirectAdmin, updating of the web files happened via FTP.
The incident was brought to the attention of the company because they received complaints … Read more.
This is a short post, put here as a “reminder to self” on browser caching.
A colleague recently set up an HTTP sinkhole with Apache. The setup redirected all the user requests to one specific resource.
When deploying the sinkhole, the web server logs showed that the first requests where logged with HTTP status code 200 (“OK”). The next requests however were logged with HTTP status code 304 (“Not Modified”).
The HTTP 304 code basically … Read more.
I had a guest post published on Security Training for Incident Handlers: The New Glibc Getaddrinfo Vulnerability: Is It GHOST 2.0?.
The post describes the critical issue found in glibc getaddrinfo (CVE-2015-7547) and gives you advice on patch management to deal with current (and future) issues in glibc.
According to isc.org “Passive DNS” or “passive DNS replication” is a technique invented by Florian Weimer in 2004 to opportunistically reconstruct a partial view of the data available in the global Domain Name System into a central database where it can be indexed and queried.
In practical terms passive DNS describes an historical database of DNS resolutions. What does this all mean? It means that you can lookup to what IP address a domain resolved … Read more.