Monthly Archives: June 2020

The most important questions to ask in a firewall rule assessment

25 June 2020

Regular firewall rule assessments are basic IT/OT security housekeeping procedures. Security staff challenges every rule after well-known industry best practice like ANY Computer or ANY Port rules, bi-directional rules, use of unsecure protocols like ftp, telnet, smb, not used rules, etc.

Nervennahrung for firewall assessment. Own work.

Picture 1: Nervennahrung for firewall rule assessments

Compliance to industry best practice can be achieved with a plain checklist. Thus the check can be automated to a far extent. The nerve-racking work starts afterwards, when each finding is discussed with the users.

But, in general, the security staff does not challenge the rule itself. Or it’s direction. Or the ports used.

These questions are asked after the rule has passed the best practice checks. No automation possible. They require in-depth knowledge of the services accessed through the firewall, and, they belong to the nerve-racking category. But it’s worth to ask these questions because

The best firewall rule is the one that not exists.

You must not care of such rules in the case of a security incident, no regular review required, no discussion with users. Entrepreneurs should be interested in cleaning up the rule base because it saves costs, and increases security.

More about this in the next post.

Picture credits

Picture 1: Vienna 2020. Own work

Australia Fights Sophisticated State-Backed Copy-Paste Attack with The Essential Eight!

20 June 2020

Reports on a wave of sophisticated nation state sponsored cyber-attacks against Australian government agencies and critical infrastructure operators spread like wild-fire through international media the day before yesterday.

From an IT security point of view, the access vector is really interesting. In Advisory 2020-008 (1) , the Australian Cyber Security Centre (ACSC) states that the actor leverages mainly a remote code execution vulnerability in unpatched versions of Telerik UI, a deserialization vulnerability in Microsoft Internet Information Services (IIS), a 2019 SharePoint vulnerability, and the 2019 Citrix vulnerability.

The name Copy-Paste for the attacks comes from the actor’s “capability to quickly leverage public exploit proof-of-concepts to target networks of interest and regularly conducts reconnaissance of target networks looking for vulnerable services, potentially maintaining a list of public-facing services to quickly target following future vulnerability releases. The actor has also shown an aptitude for identifying development, test and orphaned services that are not well known or maintained by victim organizations.” (1)

The Essential Eight

The Essential Eight (Click to enlarge)

In the advisory the ACSC recommends some really basic preventive measures like patching or multi-factor authentication. These are two controls of “The Essential Eight”(2). I like the name “The Essential Eight”. It reminds me on the 1960 Western-film “The Magnificent Seven”, reinforced by Chuck Norris 😉

The Essential Eight focus on very basic strategies to reduce the likelihood and the impact of an attack. Without them, UEBA, SIEM, Threat Intelligence, Deep Packet Inspection, PAM, etc. make few sense.

Except of multi-factor authentication, The Essential Eight are part of the feature-rich Windows and Linux OS or already (backup solution) in place. So, only some internal effort and leadership is required to dramatically increase the resilience against cyber-attacks.

The Essential Eight are a prefect weekend reading. Have fun.

References

  1. Advisory 2020-008: Copy-paste compromises – tactics, techniques and procedures used to target multiple Australian networks | Cyber.gov.au [Internet]. [cited 2020 Jun 19]. Available from: https://www.cyber.gov.au/threats/advisory-2020-008-copy-paste-compromises-tactics-techniques-and-procedures-used-target-multiple-australian-networks
  2. Australian Cyber Security Center. Essential Eight Explained | Cyber.gov.au [Internet]. Australian Signals Directorate. 2020 [cited 2020 Jun 19]. Available from: https://www.cyber.gov.au/publications/essential-eight-explained

An endless stream of SMB vulnerabilities …

11 June 2020

SMBleed, SMBLost, and SMBGhost/CoronaBlue are the vulnerabilities detected in the Microsoft SMB V3 protocol this year.

Critical SMB Vulnerabilities

Critical SMB Protocol Vulnerabilities

SMBleed/SMBGhost can be used to compromise a company network by attacking a system in the DMZ with port 445 open to the internet. Fortunately, SMBleed and SMBGhost impact only the latest Windows 10 versions. The number of Windows 10 systems directly accessible from the internet is still small.

Vulnerable Windows 10 1909 Pro Systems

Vulnerable Windows 10 1909 Pro Systems

Like EternalBlue, SMBLost impacts all Windows versions but is less critical because authentication (PR:L) is required.

The good news is that patches were available at the time the vulnerabilities were published. But it takes some weeks to implement them. During this time companies remain vulnerable against cyber-attacks.

Vulnerability management / priority patching is the standard approach to this kind of vulnerabilities. IT staff is kept busy, IT security solution and service providers make a good bargain, but the company’s resilience against cyber-attacks stays low. Companies can only hope that also the next SMB vulnerability is disclosed after a patch is available.

From an entrepreneurial point of view the obvious solution is to remove such systems from the internet. A risk assessment is imperative to evaluate the potential loss of sales and the costs of recovering from a cyber-attack. If the recovery costs exceed the potential loss of sales the system should be removed. This will slightly reduce IT costs but increase the resilience against such kind of cyber-attacks.

It is high time to evaluate IT[-security solutions] from an entrepreneurial point of view, in terms of Loss of Sales and Loss of EBIT.

Have a great weekend.

New study shows: Vulnerabilities in popular open source projects doubled in 2019. No need to panic!

9 June 2020

Catalin Cimpanu’s (1) post on the RiskSense study “The Dark Reality of Open Source” is well worth reading. Open source software is used everywhere. A critical vulnerability in an application that is based on open source software can lead to a data breach. But this holds also for commercial software. We can also expect that the number of flaws in open source and commercial software is roughly the same.

The main difference is that the number of open source software reviews is much higher than the number of commercial software reviews. So the results of the study are not really surprising.

In the case of TomCat, 7 of the 72 published vulnerabilities were weaponized. A quick check against the latest Coverity scan results for Apache TomCat (2) shows that the software has 987 defects, thereof 290 not yet fixed.

High impact defects are very valuable for attackers because their exploitation results in a full loss of integrity. The number of high impact defects in TomCat yet not fixed is 171. So we can expect that the number of vulnerabilities that can be weaponized is high.

In the case of Puppet, none of the 72 published vulnerabilities were weaponized. The latest Coverity scan for Puppet (3) shows no high impact vulnerabilities. So the result is not surprising.

What is the difference between Puppet and TomCat? Puppet is written in PHP/Python/Ruby with a defect density of 0.20. The defect density is the number of defects in 1000 LoC. TomCat is written in Java with a defect density of 1.19. Thus, software reviews will definitely detect more vulnerabilities in TomCat than in Puppet.

This has direct impact on your security strategy. If you use TomCat as middle-ware in the DMZ you should design your application to allow frequent patching, means, more robust against changes in the middle-ware. In addition, automated testing is required to ensure operability in the case a patch must be implemented. Finally, your operations team must be prepared to install patches within few hours upon release by the vendor.

Have you ever seen such details for commercial software? Like IIS?

Have a great week.

References

1. Cimpanu C. Vulnerabilities in popular open source projects doubled in 2019 [Internet]. ZDNet. 2020 [zitiert 8. Juni 2020]. Available at: https://www.zdnet.com/article/vulnerabilities-in-popular-open-source-projects-doubled-in-2019/

2. Synopsys. Coverity Scan – Static Analysis for Apache TomCat [Internet]. 2020 [zitiert 9. Juni 2020]. Available at: https://scan.coverity.com/projects/apache-tomcat

3. Synopsys. Coverity Scan – Static Analysis for Puppet [Internet]. [zitiert 9. Juni 2020]. Available at: https://scan.coverity.com/projects/puppetlabs-puppet