Category Archives: Advice for SMEs

Plundervolt. Don’t panic!

16 December 2019

Last Tuesday, Intel (1) published a patch for a new hardware vulnerability dubbed Plundervolt (CVE-2019-11157). As always with hardware vulnerabilities, Plundervolt got a lot of attention in the media.(2)(3)(4) A Google search for “plundervolt intel” shows about 167.000 hits as of today. The vulnerability was detected by a research team lead by Kit Murdock (5) some month ago.

In parallel, Microsoft published a patch for the privilege escalation vulnerability CVE-2019-1458.(6) CVE-2019-1458 is actively used in attacks (7), so it also got some media attention (Google search “CVE-2019-1458”: 88.000 hits as of today).

Plundervolt logo.

Plundervolt logo.

From my point of view, hardware vulnerabilities are always somewhat overvalued, especially in terms of their benefit in cyber operations. The vulnerabilities named RyzenFall, FallOut, Chimera and MasterKey in AMD processors, which were discovered last year, are maybe the best examples.(8) So, lets take a closer look on PlunderVolt and CVE-2019-1458.

The table below shows the CVSS V3.1 Severity for the vulnerabilities.

Plundervolt CVE-2019-1458 comparison

Plundervolt / CVE-2019-1458 comparison

The main difference is in the Privileges Required (PR) to exploit the vulnerability. For Plundervolt, Murdock et al. “assume the standard Intel SGX adversary model where the attacker has full control over all software running outside the enclave (including privileged system software such as operating system and BIOS).”(5) That means that the system must already be fully compromised before Plundervolt can be exploited.

In contrast, CVE-2019-1458 allows the attacker to acquire high privileges on a system once he hijacked a standard user account. So, by exploiting CVE-2019-1458 the attacker sets up the environment to exploit Plundervolt.

From an attacker’s point of view, CVE-2019-1458 is more valuable than Plundervolt. Once one system is compromised, the attacker can use it as base of operations for the exploration of the victim’s network. In the worst case, the Active Directory is compromised within some minutes, so the attacker has access to all secrets, or he can push ransomware to all computers.

For organized crime and APTs, CVE-2019-1458 is a universally exploitable tool to achieve goals.

Plundervolt gets interesting if the attacker is interested in encryption key details which are used internally only, for example in Transparent Database Encryption (TDE) or in trusted execution environments. Murdock et al. “demonstrate the effectiveness of our attacks by injecting faults into Intel’s RSA-CRT and AES-NI implementations running in an SGX enclave, and we reconstruct full cryptographic keys with negligible computational efforts.”(5) In the worst case, this results in the loss of all data in a TDE secured database, since vendors use Intel’s AES-NI on-chip implementation to speed up cryptographic computations.

So, Plundervolt is interesting for organized crime and APTs when it comes to industrial espionage or in attacks against targets which are relevant for national security.

Fortunately, the time frame for exploitation is short. The patch for CVE-2019-1458 will be automatically rolled out through the WSUS infrastructure within the next weeks. Plundervolt should be patched, with high priority on critical systems, if a company is target of espionage or operates critical infrastructures.

Do you know your threat profile and critical systems? Without this knowledge efficient vulnerability management is not possible. Not sure? So, take it as a New Year’s resolution…


References

  1. Intel Security Center. INTEL-SA-00289 [Internet]. Intel Security Center. 2019 [cited 2019 Dec 13]. Available from: https://www.intel.com/content/www/us/en/security-center/advisory/intel-sa-00289.html
  2. Gatlan S. Intel Patches Plundervolt, High Severity Issues in Platform Update [Internet]. BleepingComputer. 2019 [cited 2019 Dec 13]. Available from: https://www.bleepingcomputer.com/news/security/intel-patches-plundervolt-high-severity-issues-in-platform-update/
  3. O’Donnell L. Modern Intel CPUs Plagued By Plundervolt Attack | Threatpost [Internet]. threatpost. 2019 [cited 2019 Dec 13]. Available from: https://threatpost.com/intel-cpus-plundervolt-attack/151006/
  4. Khandelwal S. New PlunderVolt Attack Targets Intel SGX Enclaves by Tweaking CPU Voltage [Internet]. The Hacker News. 2019 [cited 2019 Dec 13]. Available from: https://thehackernews.com/2019/12/intel-sgx-voltage-attack.html
  5. Murdock K, Oswald D, Garcia FD, Van Bulck J, Gruss D, Piessens F. Plundervolt: Software-based Fault Injection Attacks against Intel SGX}. In: Proceedings of the 41st IEEE Symposium on Security and Privacy (S&P’20) [Internet]. San Francisco, CA; 2019 [cited 2019 Dec 13]. Available from: https://plundervolt.com/
  6. MSRC. CVE-2019-1458 | Win32k Elevation of Privilege Vulnerability [Internet]. Microsoft Security. 2019 [cited 2019 Dec 16]. Available from: https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2019-1458
  7. Kaspersky Global Research and Analysis Team. Windows 0-day exploit CVE-2019-1458 used in Operation WizardOpium | Securelist [Internet]. SECURELIST. 2019 [cited 2019 Dec 16]. Available from: https://securelist.com/windows-0-day-exploit-cve-2019-1458-used-in-operation-wizardopium/95432/
  8. Cimpanu C. AMD Confirms RyzenFall, MasterKey, Fallout, and Chimera Vulnerabilities [Internet]. BleepingComputer. 2018 [cited 2019 Dec 16]. Available from: https://www.bleepingcomputer.com/news/hardware/amd-confirms-ryzenfall-masterkey-fallout-and-chimera-vulnerabilities/

World Cafe@IMI 2019: No Backup, No Mercy!

24 November 2019

IMI 2019: Presentation DOW Cyber Security Framework

IMI 2019: Presentation DOW Cyber Security Framework

The motto of the IT meets Industry 2019 (IMI) conference in Mannheim was What happens if shit happened. During the World Cafe session, the participants dealt with the following scenario:

  1. The cyber-criminal overcame all hurdles you put in place to protect your production systems from attacks.
  2. The anomaly detection capabilities in place recognized the attack late.
  3. The engineering station (ES) is compromised.
  4. You isolated the engineering station from the network for further analysis.
  5. The good news is that the process control system (PCS) is still operable.
  6. The bad news is that it’s not clear whether the control program in the PCS is also compromised.

You decide to download the control program from the backup into the PCS. This is no uncommon scenario. The Rogue7 (1) attack described at the Black Hat 2019 and Triton (2) work this way. One of the participants put it this way: No Backup, No Mercy! Unfortunately, it’s not that simple.

Where is the current backup stored?

Under normal conditions, the current control program is stored on the engineering station. But this version is not usable because the engineering station is compromised.  If the backup is well organized, a copy of the control program is available from a NAS or a dedicated backup system

Is it really the current version?

This is very important if you want to recover the PCS to the state before the attack happened. Unfortunately, the Recovery Point Objective (RPO) in production is zero. That means, that the latest version of the control program is required for recovery. Older versions require, in the best case, manual reworking, thus a longer downtime and higher financial loss.

Is the PCS restorable from this version and fully operable afterwards?

Have you ever tried a restore test during scheduled maintenance to make sure that the PCS is fully operable after the restore of the control program? Is it clear what is meant by fully operable? Do you have a procedure and check list in place to verify this?

But the worst is yet to come. If you do daily backups there is a small chance that all backup versions are compromised.  In the above scenario, the anomaly detection system detected the attack late. If you keep for instance the latest 10 versions online and the attacker was active for 14 days, then all backups are potentially compromised. So, you must retrieve a backup from a tape library, if any.

Summary

Backup in the age of cyber attacks and ransomware is a hard job, especially in production. Without a strategy and preparation for the worst case a cyber attack may become a financial disaster. The 7 Ps Rule shows the direction in incident response:

Prior Preparation and Planning Prevents Piss Poor Performance!

Want to participate in real peer to peer knowledge exchange and a World Cafe on hot topics? Join the IMI 2020 in Mannheim.

Have a great week.


References

  1. Biham E, Bitan S, Carmel A, Dankner A, Malin U, Wool A. PPT: Rogue7: Rogue Engineering-Station attacks on S7 Simatic PLCs [Internet]. Powerpoint Presentation presented at: Black Hat USA 2019; 2019 Aug 8 [cited 2019 Aug 16]; Mandalay Bay / Las Vegas. Available from: https://i.blackhat.com/USA-19/Thursday/us-19-Bitan-Rogue7-Rogue-Engineering-Station-Attacks-On-S7-Simatic-PLCs.pdf
  2. Sobczak B. SECURITY: The inside story of the world’s most dangerous malware [Internet]. 2019 [cited 2019 May 11]. Available from: https://www.eenews.net/stories/1060123327

Application control solutions for protecting critical infrastructures

13 October 2019

Application Control Solutions (ACS) are easy to deploy and manage protective security controls in process automation. From my point of view, they are essential when it comes to critical infrastructures. The major SCADA vendors recommend and certify them for use with their product suites.

Rick Gorskie, Global Sales Manager Cybersecurity at Emerson Automation Solutions, recommends “using both solutions for an effective “one-two” punch against malware infection. Using applications whitelisting to protect from “zero-day” attacks as well as using antivirus blacklisting to scan for malware yields the best result.”(1)

Schneider Electric recommends the application control for their Power SCADA systems: “Power SCADA has been validated with the McAfee Application Control whitelisting application. Power SCADA and McAfee whitelisting can make your system more resilient to zero-day threats.”(2)

In addition to the protection against zero-days, application control allows to reduce the patch frequency and to extent the life of legacy systems.

The ACS kicks in during the exploitation phase of the Cyber Kill Chain. It checks every object at execution time whether it is known in the white list. Since new malware is not on the list, ACS just blocks the execution. This is a plain, but very effective approach.

Cyber Kill Chain - Application Control Solutions

Cyber Kill Chain – Application Control Solutions

This works for file-less malware like Nodersok (3) as well as for file-based malware like Reductor (4) or COMpfun (5). Even crypto worms like WannaCry are blocked.

In the case of COMpfun, for example, two DLLs are loaded into the users AppData directory. Both DLLs are not on the white list, so the execution is blocked although they are defined as COM objects.

Reductor uses two delivery methods, COMpfun and infected software installers. If COMpfun is used for delivery, the ACS blocks the malware.

But if the Reductor is delivered through infected software installers, ACSs will not work because they have their Achilles heels.

ACSs must be suspended during deployment or update of software.

A malware, for example a trojan disguised as part of a software suite, will become a legitimate program after the ACS is enforced again. Thus, the malware will never be blocked because it’s on the white list.

ACSs allow exceptions.

Some SCADA vendors request exceptions for the execution of some of their software tools. If malicious actors exploit these exceptions, they can inject malware outside regular installations.

So, we have a residual risk, depending on the threat actor and the environment.

For non-critical infrastructures, ACSs provides great protection against all threat actors. But in the case of critical infrastructures, APT and, to some extent, cyber criminals have the resources and the know how to exploit the Achilles heels of ACSs.

Additional security controls must be implemented to reduce this risk. Operators and engineering service providers must work together to solve this issue.

This may include an extended integrity check of all software before installation in the SCADA network and the encryption of all media during transport.

By the way, ACSs provide effective protection against zero-days only if they are not suspended. So, it’s a good idea to check regularly if the ACS agents are operated in enforced mode on the systems.

Have a great week.


References

  1. Gorskie R. Should You Be Using Application Whitelisting? [Internet]. Emerson Exchange 365. 2017 [zitiert 22. September 2019]. Verfügbar unter: https://emersonexchange365.com/products/control-safety-systems/f/deltav-discussions-questions/6792/should-you-be-using-application-whitelisting
  2. Schneider Electric. Power SCADA Operation 9.0 System Guide | Schneider Electric [Internet]. 2019 [zitiert 22. September 2019]. Verfügbar unter: https://www.schneider-electric.com/en/download/document/PowerSCADAOperationSystemGuide/
  3. Microsoft. Bring your own LOLBin: Multi-stage, fileless Nodersok campaign delivers rare Node.js-based malware [Internet]. Microsoft Security. 2019 [zitiert 28. September 2019]. Verfügbar unter: https://www.microsoft.com/security/blog/2019/09/26/bring-your-own-lolbin-multi-stage-fileless-nodersok-campaign-delivers-rare-node-js-based-malware/
  4. GReAT. COMpfun successor Reductor infects files on the fly to compromise TLS traffic | Securelist [Internet]. Kaspersky Securelist. 2019 [zitiert 12. Oktober 2019]. Verfügbar unter: https://securelist.com/compfun-successor-reductor/93633/
  5. G Data. COM Object hijacking: the discreet way of persistence [Internet]. G Data Blog. 2014 [zitiert 12. Oktober 2019]. Verfügbar unter: https://www.gdatasoftware.com/blog/2014/10/23941-com-object-hijacking-the-discreet-way-of-persistence

How to get the best ROI for investments in cyber security?

28 September 2019

During a workshop this week we had a discussion on risk management and investment in cyber security. Risk is the product of likelihood of occurrence (LoO) and severity of impact (SoI). So, to reduce the risk we can either try to reduce the SoI, or the LoO, or both.

We do risk management because we have limited resources. The big question is always: Where shall I spent my resources?  Or, where can I gain the best ROI? Shall I reduce the likelihood of occurrence or the severity of the impact? Or both?

The Cyber Kill Chain is a great model to study this.

Cyber Kill Chain - Risk Management - Cost

Cyber Kill Chain – Risk Management – Cost

We can reduce the likelihood of occurrence starting during the delivery phase up to the command & control phase. Once the attacker crosses the red line the LoO is 100 %.

The severity of impact can be reduced starting at the midst / end of the exploitation phase. WannaCry, for example, started the encryption immediately during installation of the malware and contacted in parallel its command & control server. Once the attacker crosses the red line, the impact and thus the costs for recovery are high.

The big problem with reducing the likelihood of occurrence is that we have in the best case only some seconds to minutes until the attacker crosses the red line. For efficient use of this time we need to invest in preventive or proactive means.

Cyber security awareness training, for example, is a very efficient preventive measure to reduce the LoO during the delivery and exploitation phase, because the exploitation of about 35% (Data NIST NVD, CVSS V3, UI:R) of vulnerabilities published in 2018 requires user interaction. Priority patching is another preventive measure with can stop an attacker early.

Backup and emergency recovery are great means to reduce the severity of impact. But the latest attack on Norsk Hydro makes clear that, even with the best crisis management, the recovery of some thousand systems from scratch takes some time.

When used in context with the existing security controls, the Cyber Kill Chain provides support in setting priorities in cyber security investment. The Mitre ATT@CK framework, which is based on the Cyber Kill Chain, brings the required methodology in the planning process. Give it a try.

Have a great weekend.

Threat Intelligence – What is it good for?

31 August 2019

I attended a virtual summit on threat intelligence this week. I watched two interesting presentations and found that I am still not convinced of the value of threat intelligence.

In vulnerability management for example threat intelligence speeds up decision making. But is speed in the decision-making phase of vulnerability management an issue?

OODA Loop

OODA Loop

When we deal with critical vulnerabilities, e.g. vulnerabilities of the WannyCry Class, speed is crucial. The OODA procedural model is perfectly suited as execution procedure for environments where speed is crucial for survival.

OODA, an acronym for Observe, Orient, Decide, Act, was developed by John Richard Boyd in the 1950’s as survival strategy in aerial combat. Colonel Boyd, one of the most influential military strategists ever, transferred OODA to other domains after he retired from the US Air Force.

The picture below shows the OODA procedural model adapted for vulnerability management.

OODA for Vulnerability Management

OODA for Vulnerability Management

We must decide whether urgent action is required if a new critical vulnerability is published. Data collected from OSINT sources, asset details, and experience in the evaluation of vulnerabilities are required for creating a well-founded decision.

Threat intelligence speeds up the Observe and Orient phase by e.g. providing data on exploits seen in the wild. But threat intelligence will neither replace current asset data, which are crucial for the Orient phase, nor speed up the Act phase, where the affected assets are patched, and their correct operations is verified.

So, if you decide on investing in threat intelligence ask yourself the question: What benefits do I expect to gain from threat intelligence in what use cases? Otherwise, it is very likely that you get disappointed.

Have a good weekend.

Rogue 7. A new attack on Simatic S7 PLCs. Who should be concerned?

18 August 2019

Pierluigi Paganini’s post (1) on Rogue 7, which popped-up in my LinkedIn news feed last Tuesday, immediately caught my attention. And troubled me somewhat because I am living a mile north from one of the largest German chemical industrial parks where lots of Simatic S7-1200 and S7-1500 PLCs are in operations.

The facts.

A group of Israeli security researchers managed to compromise PLCs of the Simatic S7-1200 and S7-1500 series. They presented the results at the Black Hat 2019 (2). For more technical details see the accompanying conference paper (3).

The SIMATIC developers learned from the past attacks on the S7 protocol, and integrated cryptographic protection in the latest version of the protocol. This includes a key exchange protocol for secure session set-up between the TIA and the PLC, message integrity protection, and payload encryption.

The Israeli researchers re-engineered the protocol and found some design weaknesses in the implementation which they used to execute start/stop attacks on the PLC, program download and stealth program injection attacks.

Countermeasures.

To fix the design flaws in the protocol will take some time.

With CPU access protection (4), the design weaknesses can be mitigated. Unfortunately, the default is “No Protection”, that is,” the hardware configuration and the blocks can be read and changed by all users”. So, it’s time to switch CPU access protection on, at least for high risk environments, e.g. if the PLC is directly accessible from the internet and port 102 is open.

Should we be concerned, or, to put in another way: Who should be concerned?

That depends on the target industry and the threat actor.

Critical Infrastructures.

IEC 62443 request’s that PLCs should be isolated in a separate network zone inside the SCADA partition of the production network. In the best case, communication is allowed from systems in the SCADA partition to the PLC only. If the operator follows this defense in depth strategy during production network build the risk of Rogue 7 style attack on a PLC is low.

Fortunately, operators of critical infrastructures are forced by regulations to implement a defense in depth strategy. But the effort for implementation and operation of an IEC 62443 compliant network is high. To reduce the effort, even large deviations from the IEC 62443 requirements are accepted.

Protection against APTs: The more the better? Own work. Paris 2019.

Protection against APTs: The more the better? Own work. Paris 2019.

State guided or sponsored threat actors, also called APT (Advanced Persistent Threat), and to a certain extent Organized Crime leverage these deviations in attacks on critical infrastructures. Hacktivists and Script Kiddies can be neglected because they lack the specific network infiltration and SIMATIC S7 know how.

Recall Triton, the attack on a Schneider Electric Triconex safety controller in 2017. The attackers (APT) compromised the Petro Rabigh corporate network in 2014. “From there, they eventually found a way into the plant’s own network, most likely through a hole in a poorly configured digital firewall that was supposed to stop unauthorized access.”(5)

Petro Rabigh Chemical Plant.

In June 2017, the first unplanned shutdown of a safety controller took place. Finally, on Aug. 4, 2017, at 7:43 p.m., two safety controllers brought parts of the Petro Rabigh complex offline to prevent a gas release and explosion.(6)

The attackers compromised also the PLC. “But as safety devices took extraordinary steps, control room engineers working the weekend shift spotted nothing out of the ordinary, either on their computer screens or out on the plant floor.”(6)

This describes exactly the result of the Rogue 7 program download and stealth program injection attack. The PLC runs the malicious code while the operator believes that everything is in order.

Other production environments.

The S7 protocol uses port 102 for accessing the PLC from the TIA portal, the HMI and the engineering station. The Rouge TIA or the Rogue Engineering station must connect to this port on the PLC for running the start/stop attack or the program download attack. If this port is accessible from the network, in the worst case from the internet, APTs and Organized Crime can easily compromise the PLCs. The risk that Hacktivists or Script Kiddies compromise PLCs is low because they lack of the very specific SIMATIC S7 know how.

How big is the problem? A quick check on Shodan (query: SIMATIC CPU-1200, executed 8/18/2019) shows that about 350 S7-1200 systems are directly connected to the internet, thereof only few with Port 102 open. So, no reason to panic. Most of the operators have already implemented the Siemens recommendations on ICS security.

Summary

I welcome the fact that the Israeli security researchers published the weaknesses in the S7 protocol. We can assume, that, like EternalBlue, these weaknesses are already available in stand-by in the arsenals of intelligence agencies around the globe. So, we can prepare for the next leak and, hopefully, prevent a future attack of WannaCry extent.

Direct actions are required to evaluate the current risk.

  • Check the firewall rule base to make sure, that the S7 protocol port 102 is not open for systems outside the SCADA network partition or the internet.
  • Evaluate the risk of activating CPU access protection. If acceptable, update your operating procedures, train the staff, and active CPU access protection.

For critical infrastructure operators.

  • Document every deviation from the IEC 62443 concept. Evaluate the risk with regards to the capabilities of APT and Organized Crime. Take effective protective means if the risk is not acceptable.

Have a great week.


References

  1. Paganini P. Boffins hacked Siemens Simatic S7, most secure controllers in the industry [Internet]. Security Affairs. 2019 [cited 2019 Aug 16]. Available from: https://securityaffairs.co/wordpress/89720/hacking/siemens-simatic-s7-hack.html
  2. Biham E, Bitan S, Carmel A, Dankner A, Malin U, Wool A. PPT: Rogue7: Rogue Engineering-Station attacks on S7 Simatic PLCs [Internet]. Powerpoint Presentation presented at: Black Hat USA 2019; 2019 Aug 8 [cited 2019 Aug 16]; Mandalay Bay / Las Vegas. Available from: https://i.blackhat.com/USA-19/Thursday/us-19-Bitan-Rogue7-Rogue-Engineering-Station-Attacks-On-S7-Simatic-PLCs.pdf
  3. Biham E, Bitan S, Carmel A, Dankner A, Malin U, Wool A. Rogue7: Rogue Engineering-Station attacks on S7 Simatic PLCs. In Mandalay Bay / Las Vegas; 2019 [cited 2019 Aug 16]. Available from: https://i.blackhat.com/USA-19/Thursday/us-19-Bitan-Rogue7-Rogue-Engineering-Station-Attacks-On-S7-Simatic-PLCs-wp.pdf
  4. Siemens AG. Simatic S7-1500 Security [Internet]. Siemens AG; 2013 [cited 2019 Aug 16]. Available from: https://www.automation.siemens.com/salesmaterial-as/interactive-manuals/getting-started_simatic-s7-1500/documents/EN/sec_en.pdf
  5. Giles M. Triton is the world’s most murderous malware, and it’s spreading [Internet]. MIT Technology Review. 2019 [cited 2019 May 11]. Available from: https://www.technologyreview.com/s/613054/cybersecurity-critical-infrastructure-triton-malware/
  6. Sobczak B. SECURITY: The inside story of the world’s most dangerous malware [Internet]. 2019 [cited 2019 May 11]. Available from: https://www.eenews.net/stories/1060123327

How to defend against file-less malware?

15 July 2019

Stories on file-less malware are constantly appearing in the news. Zeljka Zorz’s post “A file-less campaign is dropping the Astaroth info-stealer” (1), published on 9 July 2019 in Help Net Security, gives a great introduction into the techniques used in file-less attacks.

Andrea Lelli’s technical analysis (2) shows that the malware downloads some DLLs and injects them into the userinit.exe process after becoming persistent. So, no big development since the first report on a file-less malware, Poweliks (3), published in 2014.

Pattern based anti-malware solutions are still no effective means to protect against file-less malware because the malware uses the hacker’s favorite toolkit, the Windows OS, for installation of the malicious payload.

But there is no reason to panic. The Windows OS is part of the problem; the Windows OS is also part of the solution.

First things first.

Don’t work with permanent administrative privileges!

It cannot be repeated often enough! Userinit.exe is part of the Windows OS. Admin privileges are required to load a DLL into the userinit.exe process. So, no admin rights, no DLL injection.

Now the big change.

We need change!

We need change!

In a Windows environment, Microsoft AppLocker does the job. AppLocker is an efficient solution; it is part of the Windows OS and it can be configured centrally by group policies. AppLocker is an effective solution; all kind of dropper malware is blocked, and with DLL rules enforced, DLL injection is no longer possible. Thus, AppLocker is the perfect solution for SMBs to overcome the shortcomings of pattern based anti-malware solutions. For a brief overview on AppLocker see my post (4).

If AppLocker does not fit into your computing environment, for example in production, look at the application whitelisting solutions from the big anti-malware solution providers. Application whitelisting provides additional features, e.g. the lockdown of systems, which is of interest especially in production because of the much longer solution lifecycles.

Application whitelisting is the long overdue change in the strategic approach to cyber security. Give it a try. Once you locked down your systems you can take care of the really important issues. Like supporting your business in digitalization initiatives.

Have a great week.


References

  1. Zorz Z. A fileless campaign is dropping the Astaroth info-stealer [Internet]. Help Net Security. 2019 [zitiert 15. Juli 2019]. Verfügbar unter: https://www.helpnetsecurity.com/2019/07/09/astaroth-fileless-malware/
  2. Lelli A. Dismantling a fileless campaign: Microsoft Defender ATP next-gen protection exposes Astaroth attack [Internet]. Microsoft Security. 2019 [zitiert 15. Juli 2019]. Verfügbar unter: https://www.microsoft.com/security/blog/2019/07/08/dismantling-a-fileless-campaign-microsoft-defender-atp-next-gen-protection-exposes-astaroth-attack/
  3. Jochem K. Review – ‘Poweliks’ malware variant employs new antivirus evasion techniques [Internet]. IT Security Matters. 2014 [zitiert 15. Juli 2019]. Verfügbar unter: https://klausjochem.me/2014/08/09/poweliks-malware-variant-employs-new-antivirus-evasion-techniques/
  4. Jochem K. Windows Applocker – The almost forgotten IT security workbench [Internet]. IT Security Matters. 2019 [zitiert 15. Juli 2019]. Verfügbar unter: https://klausjochem.me/2019/01/05/windows-applocker-the-almost-forgotten-it-security-workbench/