Tag Archives: Linux

Microsoft previews Microsoft Defender ATP for Linux – No reason to celebrate!

7 March 2020

At the Ignite 2019 Microsoft announced that “Defender ATP is coming to Linux in 2020” (1). The preview version is available since the end of February (2).

To be clear, I think Microsoft Defender ATP is a good product. It benefits from millions of sensors installed on consumer and company computers. And, with the entire Defender suite installed, companies can gain a good security level.

COVID-19 Virus ultrastructural morphology

COVID-19 Virus ultrastructural morphology. Picture by CDC/ Alissa Eckert, MS; Dan Higgins, MAMS

Just to recap on why we need anti-malware products: We live in an operating system monoculture. Windows is everywhere, on the clients, on the servers, in the cloud. All windows systems are networked for reasons of efficiency. The drawback of all mononcultures is that they are vulnerable against diseases. Covid-19 is a current example in the real world, WannaCry and NotPetya are well known examples in cyber space.

Microsoft loves Linux, and starts implanting genes from the Windows DNA into the Linux DNA; the .Net framework, PowerShell, Windows Defender ATP. Since the cost pressure in IT is high, companies will start using this products.

Good for the EBIT, bad for cyber security. PowerShell for example is often used in malware attacks (3). It’s merely a matter of time before cyber attackers start leveraging PowerShell on Linux. Living off the Land attacks will work on Linux and Windows, in the worst case with no changes to the code. With that, Linux is getting vulnerable against attacks that were so far only known from Windows.

Especially for operators of critical infrastructures is a clear strategy for operating Microsoft products on Linux required to keep the risk from this cross-over at an acceptable level.

For advice in securing PowerShell see publication “Securing PowerShell in the Enterprise” of the Australian Cyber Security Center (4).

Have a great weekend!


  1. Tung L. Microsoft: Defender ATP is coming to Linux in 2020 [Internet]. ZDNet. 2019 [cited 2020 Mar 7]. Available from: https://www.zdnet.com/article/microsoft-defender-atp-is-coming-to-linux-in-2020/
  2. Vaughan-Nichols SJ. Microsoft previews Microsoft Defender ATP for Linux [Internet]. ZDNet. 2020 [cited 2020 Mar 7]. Available from: https://www.zdnet.com/article/microsoft-previews-microsoft-defender-atp-for-linux/
  3. Help Net Security. 91% of critical incidents involve known, legitimate binaries like PowerShell [Internet]. Help Net Security. 2018 [cited 2020 Mar 6]. Available from: https://www.helpnetsecurity.com/2018/06/28/incidents-legitimate-binaries/
  4. Australian Cyber Security Center. Securing PowerShell in the Enterprise | Cyber.gov.au [Internet]. Australian Signals Directorate. 2019 [cited 2020 Mar 6]. Available from: https://www.cyber.gov.au/publications/securing-powershell-in-the-enterprise

HiddenWasp malware targets Linux systems – Don’t Panic!

23 June 2019

Ignacio Sanmillan’s excellent post(1) on the HiddenWasp malware could have been truly frightening: HiddenWasp targets Linux systems, the technology used is really impressive, and the detection rate on VirusTotal was zero as of 29 May 2019.

Unfortunately, the infected systems were already under the attacker’s control. Even if anti-malware solutions for Linux would have better detection capabilities it would hardly have mattered. Also, there is no need to implement sophisticated anti-malware evasion technologies. In the easiest case, the attacker must only define an anti-malware exception for the files to be downloaded.

Pattern based anti-malware solutions are reactive protective means. The anti-malware solution provider must first analyze the new malware and create a detection pattern. Thus, it is unsurprising that the detection rate on VirusTotal was and is still low.

The big questions remain open:

  • How was the RAT (Remote Access Trojan), the precondition for the infection with HiddenWasp, initially installed?
  • How did the attackers get root privileges?

Very often, it is lack of cyber hygiene that results in the takeover of a system. Implementation of cyber security best practice will raise the bar. Extended by a restrictive SELinux configuration will reduce the likelihood of getting compromised dramatically.

It’s free, and ready-to-use.

Have a great week.

  1. Sanmillan I. Intezer – HiddenWasp Malware Stings Targeted Linux Systems [Internet]. Intezer. 2019 [cited 2019 Jun 2]. Available from: https://www.intezer.com/blog-hiddenwasp-malware-targeting-linux-systems/

SambaCry – Keep Calm and Carry on

28 May 2017

Actually, it was only a matter of time until Samba, the popular implementation of the Windows SMB services on Linux and Unix, was hit by a WannyCry akin malware. All version of Samba from 3.5.0 onwards are vulnerable to CVE-2017-7494 or SambaCry.

The good news is that this vulnerability is complex to exploit: An attacker must upload a shared library with the malicious code to a writable samba share and then cause the server to load and execute it. Patches are available for the major Linux distributions.

How large is the problem? Shodan finds 471,578 systems which are exposed to the Internet.

SambaCry Shodan Map

SambaCry Shodan Map. Click to enlarge.

90% of the systems are operated in 3 countries, United Arab Emirates, Argentina, and Italy by the major telecommunication providers in these countries. Since an older version of Samba is used on this internet routers they are not vulnerable against SambaCry.

Most of the work has to be done in the United States and Germany. Although only 2 % of the affected systems are operated there, many organizations are affected.

Don’t panic! Even though many systems are affected by SambaCry this does not mean, that they are vulnerable against the exploit. Remember, you have to upload the malicious code to a writable Samba share on a server first. Under normal conditions, Linux admins don’t open Samba shares writable to everyone on servers exposed to the internet.

Thus, the best approach to reduce the risk is to check the Linux systems at the network perimeter with publicly available Samba shares and to close the writable, if any. As always, it is good to have an up-to-date system inventory in place. This will reduce the amount of work dramatically.

Take care! And don’t forget to check the network perimeter to your production networks.

LIFARS: Hackers Disable ‘Smart’ Rifle and Change Its Target, Remotely

4 August 2015

When I read the LIFARS post ‘Hackers Disable ‘Smart’ Rifle and Change Its Target, Remotely’ I felt really appalled. Not so much because the rifle’s built-in Linux server was compromised, but rather because the software developers ignored really all requirements about security and safety. Just one example from the post:

Every rifle contains a built-in network password that’s default and cannot be changed.

I do not know what planet these developers are living on, but it’s definitely not the earth.

From my point of view the software must force the marksman to change the password before he fires the first shot. In addition, Two Factor Authentication is mandatory in safety relevant cases, on a transaction basis, and with the second factor always entered directly on the rifle. Preferably through a custom grip, like the Walter PPK which Q gave to 007 in Skyfall.

Imagine security and safety standards are such bad in the billions of devices making up the Internet of Things universe. With this Doomsday is no longer just a religious concept …

Sleep well!