Category Archives: Security

Security: If it doesn’t hurt, you’re doing it wrong!

The Informationsverbund Berlin-Bonn (IVBB), the secure network of the german government , was breached by an unknown hacker group. Okay, a secure government network might be a worthy target for an attack, but your network not, right? Do you use the same password for multiple accounts? There were multiple massive data breaches in the past. Have you ever checked if your data were also compromised? I can recommend haveibeenpwned.com. If you want to have some fun, scan GitHub for -----BEGIN RSA PRIVATE KEY-----. Do you use a full disk encryption on your laptop or PC? Do you sign and/ or encrypt emails using S/MIME or PGP? Do you use different passwords for different services? Do you use 2FA/ MFA to secury importan services? Do you never work with admin privileges when doing normal office tasks? No? Why? Because it’s uncomfortable to do it right, isn’t it? read more

NetScaler native OTP does not work for users with many group memberships

Some days ago, I have implemented one-time passwords (OTP) for NetScaler Gateway for one of my customers. This feature was added with NetScaler 12, and it’s a great way to secure NetScaler Gateway with a native NetScaler feature. Native OTP does not need any third party servers. But you need a NetScaler Enterprise license, because nFactor Authentication is a requirement.

To setup NetScaler native OTP, I followed the availbe guides on the internet.

The setup is pretty straightforward. But I used the AD extensionAttribute15  instead of userParameters, because my customer already used userParameters  for something else. Because of this, I had to change the search filter from  userParameters>=#@  to extensionAttribute15>=#@ . read more

Meltdown & Spectre: What about Microsoft Exchange?

On January 18, 2018, Microsoft has published KB4074871 which has the title “Exchange Server guidance to protect against speculative execution side-channel vulnerabilities”. As you might guess, Exchange is affected by Meltdown & Spectre – like any other software. Microsoft explains in KB4074871:

Because these are hardware-level attacks that target x64-based and x86-based processor systems, all supported versions of Microsoft Exchange Server are affected by this issue.

Like Citrix, Microsoft does not offer any updates to address this issue, because there is nothing to fix in Microsoft Exchange. Instead of this, Microsoft recommends to run the lates Exchange Server cumulative update and any required security updates. On top, Microsoft recommends to check software before it is deployed into production. If Exchange is running in a VM, Microsoft recommends to follow the instructions offered by the cloud or hypervisor vendor. read more

Meltdown & Spectre: What about HPE Storage and Citrix NetScaler?

In addition to my shortcut blog post about Meltdown and Spectre with regard of Microsoft Windows, VMware ESXi and vCenter, and HPE ProLiant, I would like to add some additional information about HPE Storage and Citrix NetScaler.

When we talk about Meltdown and Spectre, we are talking about three different vulnerabilities:

  • CVE-2017-5715 (branch target injection)
  • CVE-2017-5753 (bounds check bypass)
  • CVE-2017-5754 (rogue data cache load)

CVE-2017-5715 and CVE-2017-5753 are known as “Spectre”, CVE-2017-5754 is known as “Meltdown”. If you want to read more about these vulnerabilities, please visit meltdownattack.com. read more