Tag Archives: Antivirus products

Ransomware in der Automatisierungstechnik. RoSI in der Praxis.

6. Mai 2021

Nach der kurzen Einführung in die Theorie von RoSI nun ein Praxisbeispiel.

Szenario

Ein Unternehmen betreibt an 2 Standorten prozesstechnische Anlagen. Jede Anlage besteht aus 5 Teilanlagen. Insgesamt werden pro Standort 100 Workstations und 20 Server betrieben. Die Standorte sollen im Rahmen eines Digitalisierungsprojektes enger mit der Forschungs- Entwicklungsabteilung sowie den Produktionsplanungssystemen und der Office-Cloud vernetzt werden. Vorab führt das Produktionsmanagement eine Risikoanalyse durch.

Die Risikoanalyse ermittelt ein hohes Risiko in Bezug auf eine Malware-Infektion, die zu einem Stillstand an beiden Standorten führen könnte. Der Produktionsmanager schätzt, dass eine Infektion mit Ransomware im ungünstigsten Fall zu einem Produktionsausfall von 5 Tagen führen könnte. Ein Tag Produktionsausfall kostet das Unternehmen 200T€.

Die Geschäftsleitung macht klar, dass unter der geschätzten Auslastung für die nächsten 36 Monate ein Ausfall von max. 1,5 Tagen pro Jahr akzeptabel ist. Das ermittelte Risiko ist nicht akzeptabel ist. Die OT-Security erhält die Aufgabe, die wirtschaftlich beste Lösung zur Reduktion des Risikos um 70% (von 1Mio. € auf 300T€) zu ermitteln.

Damit sind die Randbedingungen für die RoSI-Betrachtung festgelegt:

KE: Die Kosten des Sicherheitsereignisses KE belaufen sich auf KE = 1 Mio. €.

SR%: Sicherheitsmaßnahme S soll das Risiko um SR% = 70% reduzieren.

KES: Die Kosten des Sicherheitsereignisses sollen reduziert werden auf KES <= 300T€

Design der Maßnahmen

Das Unternehmen setzt in der Produktion noch keine Antimalware-Lösung ein. Zur Risikoreduzierung werden 3 traditionelle Ansätze verfolgt, die auf Sicherheitslösungen beruhen, die vom Hersteller der Automatisierungslösung freigegeben sind.

Alt1: Antimalware-Lösung McAfee Endpoint Protection

Alt2: Antimalware-Lösung McAfee Endpoint Protection plus Microsoft AppLocker

Alt3: Antimalware-Lösung McAfee Endpoint Protection plus McAfee Application Control

Microsoft AppLocker ist eine Application-Directory-Allow-Listing-Lösung, die von vielen Herstellern von Automatisierungslösungen zur Grundhärtung der Systeme empfohlen wird. AppLocker ist seit Windows 7 in der Enterprise-Version des Betriebssystems verfügbar. McAfee Application Control ist eine system-basierte Application-Whitelisting-Lösung, die von vielen Herstellern von Automatisierungslösungen zum Schutz vor bekannter und neuer Malware empfohlen wird. Sie kann auch Crypto-Würmer wie WannaCry und NotPetya, die sich im Systemkontext von System zu System bewegen, abwehren.

Bewertung der Effektivität der Lösungsansätze

IT- und OT-Security führen eine Bewertung der Effektivität der verschiedenen systemtechnischen Ansätze durch. Daraus ergibt sich folgendes Bild:

Bewertung der Effektivität der Lösungen. Zum Vergrößern klicken.

Die klassische Antimalware-Lösung „pattern-based Antivirus“ hat mit 38% eine unzureichende Schutzwirkung, ebenso wie die Lösung „Application Directory Allow Listing“ und die Kombination aus AV.Trad und AWL.DIR.

Die „system-basierte Application-Whitelisting-Lösung“ kommt bereits sehr nahe (64%) an die geforderte Risikoreduzierung SR% = 70% heran.

Die Kombination aus AV.Trad und AWL.SYS kommt am nächsten an die geforderte Risikoreduzierung von 70% heran.

Die Details zur Bewertung stehen hier bereit.

Kostenbetrachtung

Die Kosten aller Lösungen wurden untersucht. Lizenz- und Betriebskosten wurden über einen Zeitraum von 3 Jahren betrachtet. Die Kosten für die Erstinstallation wurden berücksichtigt. Bei den Lizenzkosten wurden Lizenzstaffeln (101-250 Workstations und 26-50 Server) berücksichtigt. Preise wurden per Internet-Recherche ermittelt. Das Kostenmodell steht hier zum Download verfügbar.

RoSI

Die Berechnung von RoSI über 3 Jahre ergibt folgendes Bild:

RoSI der Lösungen im Vergleich. Zum Vergrößern klicken.

Alle Lösungen haben ein positives RoSI. Die Optionen Alt1: AV.Trad und Alt2: AV.Trad + AWL-DIR scheiden aus, da das Restrisiko KES deutlich höher ist als die geforderten 900T€

RoSI: Vergleich der Alternativen. Zum Vergrößern klicken.

Alternative Alt3: Antimalware-Lösung McAfee Endpoint Protection plus McAfee Application Control und McAfee Application Control führen zu einer ähnlichen Risikoreduktion. Alt3 hat jedoch deutlich höhere Kosten.

Für welche Lösung wird sich die Produktionsleitung entscheiden?

Dies ist der letzte Post aus der Ransomware/RoSI-Reihe. Mehr zu RoSI gibt es beim IMI Virtuellen Dialog „Costs and Benefits of Security“ am 11.05.2021. Neben praktischen Anwendungsbeispielen von ABB und Fortinet erweitere ich diese Analyse um eine moderne EDR-Lösung.

Viel Erfolg mit RoSI!

Policies are an effective means for dealing with malware

5 March 2016

This week I was flooded with spear phishing emails in the office. Most of them dealt with late payment of invoices. In any case the attackers requested to study an attached file and to take immediate action to avoid the accrual of penalties.

Fortunately, the anti-virus scanner on the email gateway removed the payload from the attached zip files and filed the emails in the junk folder:

--------Begin Virus scanner message-----------------------------------------------
The company security policies do not allow to transfer file attachments of the specified type.
Removed attachment(s): B56d48d430000.000000000001.0004.mml; invoice_kOUEsX.js
--------End Virus scanner message-------------------------------------------------

It is important to note that the virus scanner removed the attachments because the company policy does not allow the transfer of such files with email. For the exchange of JavaScript files with a partner other secure communication channels must be used.

With this, the inherent risk of classic anti-malware systems is reduced. Unwanted attachments are removed even if they have not yet been identified by the anti-malware system.

Sending the payload in nested zip files is an often used technology to outsmart antivirus systems. Therefore, it is very important to let the antivirus system do in-depth scans on all attachments, even though many users will complain about this because in-depth scans delay the delivery of emails by some seconds. In the case an antivirus system cannot deal with nested archives just remove any content from the outer archive. Some more false positives are better than rebuilding hundreds of computers in the company network.

The malicious JavaScript attachment invoice_kOUEsX.js is identified by 33 of 55 antivirus systems on VirusTotal.com. Microsoft Defender identifies the file as TrojanDownloader:JS/Nemucod. And as always, the few relevant lines of code are hided in a mess of statements.

Have a good weekend.

Marco viruses on the rise – The Sleeping Beauty slumber is over

28 February 2015

For some month reports about macro viruses are constantly appearing in the IT press. Although the latest report, ‘Macro viruses reemerge in Word, Excel files’, published by Michael Heller on the TechTarget platform SearchSecurity at 24 February 2015, could make us feel somewhat insecure, there is in my opinion no reason to panic.

From the statistics created by security firm Kaspersky, we see that attackers used Microsoft Office in 1% of all cases for the distribution of exploits in 2014. In total Kaspersky products detected and neutralized 6.167,233,068 cyber-attacks in 2014. This means that Word or Excel were used in 61,763,330 cyber-attacks, 2.3 times more than in 2013.

Sounds anything but dangerous. Moreover, we are better prepared than 15 years ago, when macro viruses were most popular. Many protection measures are common sense, but sometimes it’s good to recap.

With that, I suggest:

  1. Please make sure that your anti-malware program is always up-to-date.
  2. Configure Macro Settings in Microsoft Office Trust Center. Choose ‘Disable all macros with notification’ as default:

    Disable Macros With Warnings Settings in Trust Center

    ‘Disable all Macros With Notifications’ in Trust Center

  3. Use Windows Update to keep Microsoft Office and Windows up-to-date with the latest patches.
  4. On 64 bit Windows please activate ‘enhanced Protection Mode’ in Internet Explorer. This will force Windows to run Internet Explorer in Container Mode at low integrity level. In addition, please download all files to the default download location.
  5. Enable SmartScreen Technology in Internet Explorer. Malicious files are downloaded from malicious sites. SmartScreen Technology supports you by blocking downloads from known malicious sites.
  6. Try working with standard user rights. This limits the impact of an attack to the operating system
  7. The last and perhaps the most important rule: Think twice before you click on a word or excel file stored in an untrusted site. As a rule of thumb the entire Internet is an untrusted site, and of course all email attachments.

There’s really no need to panic. Macro viruses are no rocket science. The available protection measures are enough to deal with this old stuff.

Have a good weekend!

Poweliks it is still stuck in my mind

17 August 2014

It may sound funny, but Poweliks is still stuck in my mind. The bad news for me is: Poweliks resides only in Windows registry.

The good news is: To start at every login the malware uses the Windows registry, namely the outdated method of using the [HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run] key.

And this is exactly the vulnerability of Poweliks we can use for taking counter measures!

The Windows policy ‘Do not process the legacy run list’ could be used to block Poweliks. If enabled this policy blocks the programs listed in the run key from getting executed during login. That’s it!

Do Not Process Legacy Run List Policy

Do Not Process Legacy Run List Policy

To enable the ‘Do not process the run once list’ policy start the local group policy editor gpedit.msc and navigate to section User Configuration\Administrative Templates\System\Logon. Double click the policy, select option ‘Enabled’, enter a comment and click ‘Apply’.

Use policy ‘Run these programs at user logon’ to whitelist the programs which you want to start at login. To prevent unwanted programs from getting started during system boot, enable the ‘Do not process the run once list’ in Computer Configuration as well.

Sounds somewhat strange, like fighting fire with fire. A much better solution would be to isolate all applications in AppContainers like Internet Explorer and run them at integrity level “Low” when connected to whatever network.

Microsoft, please do us this favour in Windows 10 the latest!

Review – ‘Poweliks’ malware variant employs new antivirus evasion techniques

9 August 2014

On 4 August 2014 Brandan Blevins talks in his post ‘‘Poweliks’ malware variant employs new antivirus evasion techniques‘ about a new malware which uses new infection routes.

My first thought was: Oh no, not another new malware that could not be detected by state-of-the-art Anti Virus systems!

My second thought was: Hold on for a moment. The Poweliks malware appears to jump into our computers like a deus ex machina! Sounds like magic, doesn’t it?

If you dig somewhat deeper, you find, that to implant the malware, attackers must exploit a vulnerability of the system and, the good faith of the users. In this case the media was a Word attachment of an email and a flaw in the MSCOMCTL.OCX described in CVE-2012-0158.

In section ‘What might an attacker use the vulnerability to do?’ Microsoft describes the impact:

Bacteriophage P2. Source: Mostafa Fatehi

Bacteriophage P2. Source: Mostafa Fatehi

‘An attacker who successfully exploited this vulnerability could gain the same user rights as the logged-on user. If a user is logged on with administrative user rights, an attacker who successfully exploited this vulnerability could take complete control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights…’.

And this is exactly what the Poweliks malware does.

What countermeasures could we take?

(a) Do not open attachment and files from untrusted sources like email. Common sense can prevent lots of malware attacks.

(b) Do not work with permanent administrative rights.

(c) Change the User Account Control (UAC) Settings to the highest level ‘Always notify’. The malware installs Powershell, if not already installed. In this case UAC will notify you.

(d) Check whether the latest updates and patches are installed. CVE-2012-0158 was fixed in 2012 and can not be used for an attack, if Windows Update is configured to automatically install updates.

(e) Review the Trust Center Settings in Microsoft Office.

Activate ‘ Disable all macros with notification’ in section ‘Macro Settings’,

Activate ‘Prompt me before enabling all controls with minimal restrictions’ in section ‘ActiveX Settings’.

Activate ‘File Block Settings’ except for Office 2007 or later formats in section ‘File Block Settings’.

(f) Check your AV providers Homepage for the latest updates or utilities. I bet you will find some Information or tool which could support you in an emergency.

(g) Don’t Panic!

Have a good Weekend

BadUSB – Don’t fall into a doomsday mood!

2 August 2014

When Karsten Nohl published his research on 21 July 2014, BadUSB spread throughout the media within hours. One had the feeling that the end of the world arrives at the door. Millions of  potentially compromised USB sticks could take over control of all other USB devices.

But the worst is yet to come: We are utterly powerless! Antivirus products of whatever vendor could not block this kind of attack.  As if we did not know, that Antivirus products are of limited value today.

My first reaction was: Keep cool! It’s just a proof of concept. It’s not in the wild! And the best is: It’s a very complex task, and therefore not lucrative for normal attackers.

Vulnerabilities in the handling of USB devices are not new. A search in the U.S. National Vulnerabilty Database (NVD) shows 4 high severity flaws in the past 18 month. Moreover, it is well-known that viruses are very often spread through USB devices. We all know the risk!

And even the vulnerabilities in onboard controllers are not new. Mathieu Stephan reports in his post ‘Hacking SD Card & Flash Memory Controllers’ from 29 December 2013 that the Firmware of SD Card’s was compromised. Take a look at the Video in his post.

Marshall Honorof’s post ‘Don’t Panic Over the Latest USB Flaw’ from 1 August 2014 saved my day.

At the end of his post Marshall sums it up: ‘Make no mistake: BadUSB is a fantastic proof-of-concept, and lays bare some serious problems with USB stick security. But, like anything else in the world of computing, you can avoid trouble using a little common sense.‘

To be honest, I expect a technical solution to the BadUSB trouble within the next month. Otherwise the USB stick market will collapse.

But in the meantime: Don’t Panic!