Tag Archives: Threat Intelligence

Critical vulnerabilities require immediate action – How to prevent Equifax like attacks

23 September 2017

Critical Vulnerabilities are

  • exploitable from the network (Access Vector: Network),
  • require only low or medium skills to exploit (Access Complexity: Low or Medium),
  • require no authentication (Authentication: None),
  • cause great damage (Severity: High), and
  • allow remote attackers to execute arbitrary code on the victims’ computer

Among the vulnerabilities with CVSS vector (AV:N/AC:L/Au:N) or (AV:N/AC:M/Au:N) which cause great damage the last property makes the difference.

The infographic below shows that the number of critical vulnerabilities (320) is very small compared to the total number of vulnerabilities in 2016.

Critical Vulnerabilities 2016

Critical vulnerabilities 2016. Click to enlarge.

Nevertheless, immediate action is required because the reach of attacks is technically unlimited if critical vulnerabilities can be exploited.

Once an attacker has exploited a critical vulnerability in the DMZ he is able to execute arbitrary code on this computer. With this, he can probe the network for other computers with critical vulnerabilities or leverage Windows built-in weaknesses, configuration issues, and tools to explore the network until he finally gets to a computer which has a connection across a firewall to the company network.

Both, NotPetya and WannaCry exploited critical vulnerabilities. While WannaCry was just annoying, NotPetya caused multi-million dollar damage in companies across the world.


The TEAM approach for handling risks shows the direction for dealing with critical vulnerabilities.

Transfer: No insurer will take the risk because in the case of a critical vulnerability on a server in the DMZ both the probability of occurrence and the impact are high.

Eliminate: Is not possible, because this will result in loss of business.

Accept: No option because the probability of occurrence and the impact are high.

Mitigate: Patching is the only possible response in this case. Isolation of the system from the network will result in loss of business.


Under normal conditions, patches are available at the time of disclosure.

Rule: Critical vulnerabilities should be patched faster than exploits show up on the market.

With this, immediate action is required because very often exploits are available yet at the time of disclosure. In addition, we cannot expect that only ethical hackers publish vulnerabilities.


Critical Vulnerabilities Mitigation Process

Critical vulnerabilities mitigation process.

In the Equifax attack the critical vulnerability CVE-2017-5638 in the Apache Struts framework was used. A patch was available at the time of disclosure but apparently not applied.

Patching the Apache Struts framework is a challenging job.

Firstly, it is a challenge to identify the systems with the vulnerable framework installed.

Secondly, patches must be carefully tested prior implementation to avoid business loss.

Finally, the patches must be implemented manually because automated patch management is not available.

Thus, an up-to-date asset repository, a current QA system, and actual automated test routines are required to get the job done in the required short time frame.

To be honest, the Equifax attack remains a mystery for me. The IT shop of a billion dollar company should be able to deal with critical vulnerabilities in the required short time. Perhaps someone simply underestimated the risk.

For more details on the Equifax attack see Steven Bellovin’s post Preliminary Thoughts on the Equifax Hack published at CircleID.

Have a great weekend.


Threat intelligence is the new Hype, but can threat intel actually defend you against future attacks?

19 January 2016

Can threat intel actually defend you against future attacks?

Tim Holman’s answer is simple, although not surprising:

‘Most of the time, yes. But by far the best way is to take a pro-active approach, presume attackers are already on the inside and tailor your defences from the inside out.’

For effective treatment of the inevitable he recommends to invest in a ISMS:

‘No firm can ever defend against 100% of attacks, 100% of the time, but without a doubt you can create resilient systems and business processes that are 100% effective in restoring your firm to business-as-usual when the inevitable cyber attack happens.’

For the full report please see ‘Security Think Tank: Security intelligence demands getting the basics right‘ published on ComputerWeekly.com

 Have a good day.

To be successful a SIEM implementation should follow the ISO 27001 approach

20 July 2015

Last Wednesday I participated in a workshop on Production IT Security in Frankfurt. The presentations about Security Assessments, SIEM solutions, Next Generation Firewalls and Threat Intelligence were very interesting, but, as always, I got the most valuable information from the discussions with the other attendees during coffee break. It was really amazing to hear that the attendees, although they came from different companies, talked about the same mostly negative experiences in their SIEM projects.

During my ride back to Leverkusen I had time to think about this. Expectation management was a big issue in the discussions. The PowerPoints of the vendors suggest a quick and easy installation and start-up, and with some days training in Big Data methods the SIEM operator can set up dashboards which show the current security status of your company. Far from it!

The key capabilities of a SIEM solution are:

(1) Data aggregation and correlation:  Collect event data from various sources, correlate them, and integrate them with other information sources to turn the data into useful information.

(2) Compliance: Gather compliance data to support security, governance and auditing processes.

(3) Retention and Forensic analysis: Long term storage of historical event data for correlation over time and forensic analysis in the case of a security incident.

(4) Dashboard: Turn aggregated and correlated data into informational charts to aid security staff in identifying abnormal usage patterns.

(5) Alerting: Automated analysis of correlated events and production of alerts, to notify recipients of immediate issues.

The implementation of each function requires a big effort in preparation and operation. Let me show this by the means of two examples:

(4) Dashboard. In order to find abnormal usage patterns you have to define normal usage patterns first. This takes not only time. It is really hard to find relevant patterns from the ocean of events that systems create during normal operation. To ensure fast start-up it is required to cleanup your systems of e.g. event errors created by mis-configured services before you start operation.

(5) Alerting is probably the most interesting capability of a SIEM system. It allows you to act directly upon security incidents. To get the most of alerting you have to set up an incident response process, ideally depending on the classification of the information assets to prevent wasting of time and effort.

This requires that all assets are listed in an asset repository, classified and an asset owner is assigned, before your SIEM solution goes into production.

In addition it is required that your SIEM operations group is sufficiently staffed, the operators are well-trained, and enabled to take proper actions on an incident, e.g. alerting your server operators or shutting down a server to prevent larger damage.

Sounds like the preparations required for the implementation of an Information Security Management System due to ISO 27001.

With this my advice is: For a successful and quick SIEM implementation you should follow the major steps for implementation of an ISMS.

Bonne semaine!