How they swindle $100,000 without blinking an eye – Forensic Analysis of a BEC (Business Email Compromise) (IV)

26 de November de 2020 Por
See the first part of this series, with some notes on the full series content, the second part and the third part

In the previous article, we saw how the attackers had been monitoring and manipulating the MINAF CEO’s email at will … and that they had done it through OWA (Outlook Web Access), the Exchange webmail.

To know how these logs work, we have to see how Exchange works. If we simplify it a lot, Exchange has two main components: CAS (Client Access Server) and DAG (Database Availability Group), which would be roughly equivalent to a web server and the database of a web application.

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How they swindle $100K without blinking an eye – Forensic Analysis of a BEC (Business Email Compromise) (III)

6 de November de 2020 Por
See the first part of this series, with some notes on the full series content, and the second part.

In the previous article we verified that a series of emails had been sent from the MINAF CEO’s account to the CFO, and through social engineering a series of unauthorized transfers had been made. We are at a point in the investigation where we want to know more about those emails, and for this we have to go to the low-level database of Exchange: EventHistoryDB.

EventHistoryDB is a database that collects with minute detail the entire life cycle of an email in Exchange. Thanks to EventHistoryDB we can know such granular details as:

  • When an email was written.
  • When it was sent.
  • Whether or not it was read by the recipient, and when.
  • If the mail was moved to a folder.
  • If the email was answered.
  • If the mail was sent to the trash, or even if it was deleted from it.

Unfortunately, not everything is perfect in the EventHistoryDB. It is only accessible via Powershell (no nice graphical interfaces), and only the last 7 days are saved by default. However, in this case the MINAF has reacted very quickly and this has allowed us to enter comfortably within that time frame, so it is possible to fully recover the records for the two affected users.

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How they swindle $100K without blinking an eye – Forensic Analysis of a BEC (Business Email Compromise) (II)

23 de October de 2020 Por
See the first part of this series, with some notes on the full series content.

We left the previous article with many gaps in the mail coverage from both the CEO and CFO of the MINAF. A first (and above all) quick solution is to use the MessageTracking logs. As we have already mentioned, MessageTracking is a high-level Exchange log that provides us with some basic data about the message (origin, destination, date and subject) along with some low-level identifiers (of which we will tell something in due course since they will be fundamental in our investigation).

To give you an idea, this is what a MessageTracking log (that we have minimally adapted) looks like:

If we open the log and take a quick look at it, we find a wave of messages (about 1000) quite worrisome:

(Remote data device deletion confirmation / abelardo.alcazar@minaf.es)

Apparently someone ordered the remote deletion of Abelardo Alcázar’s mobile device, something that can be done from Exchange if the terminal is configured correctly (very useful in case of theft or loss, since we do not require a remote management solution for mobile terminals or MDM).

This log agrees with Abelardo Alcazar’s statement, coinciding with the dates (remember that in Spain in summer we are at UTC + 2, so 18.47h UTC becomes 20.47h Spanish time).

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Threat hunting (VI): hunting without leaving home. Creating our victim

20 de October de 2020 Por
See previous posts: I: intro 1, II: intro 2, III: Kibana, IV: Grafiki, V: Jupyter Notebooks.

Welcome to this new post on our home laboratory, which is gradually growing more and more.

In this article we will create a testing machine to play without fear, and we will deal with the necessary configurations to log everything that happens in it.

In the second post we talked about the existing event repositories, more specifically about the Mordor project and the EVTX-ATTACK-SAMPLES repository.

These repositories are very useful for understanding and learning about how many threats behave, and they make the work much easier, but when the work is already done you don’t learn as much. With your own machine we can try out new techniques and see how they are detected in the laboratory.

It is important to bear in mind that it will not be a virtual machine in which malware will be executed, as the level of isolation will not be sufficient to guarantee the security of the host computer.

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How they swindle $100K without blinking an eye – Forensic Analysis of a BEC (Business Email Compromise) (I)

19 de October de 2020 Por

Note 0: This series of articles is a description (hopefully entertaining) of the case study (fictional, beware) that Maite Moreno and myself presented at the c1b3rwall digital security and cyber-intelligence conference, organized by the Spanish National Police. If you want more information on CEO scams you can check the (in Spanish) slides of our talk,full of data as well as a real case that we researched.

Note 1: We emphasize that this case is fictitious. However, the techniques and procedures used are identical to those used by the attackers, with the difference that we offer evidence to study them in detail. Note that he investigation could have been done more efficiently, but we wanted to show some interesting elements and techniques to deep into Exchange, hence the steps taken.

Note 2: Before starting the case study… you can play it! We have set up an open-access forensic CTF you can use to practice your technical skills. Try it before reading these articles (recommended), or later to reinforce concepts. If you only want the raw evidence, you can get them here. You can also download the step-by-step guide with all the tools and evidence needed for each step of the articles, perfecto to continue with the slides.

Those of us who work in incident response and forensics would love want attackers to warn us before doing their wrongdoing. We want it together with the Lamborghini, the yacht and the unicorn with a rainbow in the background, but we get the same response in almost all cases: no f****** way.

“What a pain in the ass it is to have an incident at 14:55 on a Friday,” you would think. There are worse things: a call from your boss at 15h on a Saturday while you are taking a nap: “Grab your incident suitcase, ‘we’re going to party’».

The party consists of about 4 hours of travel from Madrid to Ponferrada, where the headquarters of the MINAF (Minerías Alcázar y Ferrán) is located. MINAF is a mining company that will not ring a bell, but which has a turnover of more than 40 million euros and operates in 12 countries.

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Threat hunting (IV): hunting without leaving home. Jupyter Notebooks

15 de October de 2020 Por
See previous posts: I: intro 1, II: intro 2, III: Kibana, IV: Grafiki.

Do you remember the first post when we talked about what is and what is not Threat Hunting? Well, an essential part of it is the generation of intelligence.

It’s good that we are the best at detecting abnormal behavior, but if all that acquired intelligence is not transformed into structured and repeatable information we lose one of the most valuable parts of the process.

Structured, so that anyone other than the author can use it and understand it. Repeatable in the better way possible, so that the detection teams can generate alerts with it or so that any other analyst can perform the queries in the most comfortable way possible.

In our laboratory we are going to use another part of HELK, the all powerful Jupyter Notebook.

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Sandbox evasion: Identifying Blue Teams

12 de October de 2020 Por

Last March, Roberto Amado and I (Víctor Calvo) gave a talk at RootedCON 2020 titled Sandbox fingerprinting: Avoiding analysis environments. The talk consisted of two parts, the first of which dealt with classifying public sandbox environments for malware analysis, and the second with demonstrating whether it was possible to identify and even attack the person analyzing our samples. This second part is the one that will occupy this entry.

Introduction

During Red Team exercises it is always important to know who you are dealing with, their security measures and who is managing them. At this point we wondered if it would be feasible to reach the Blue Team and to know if our devices had been identified and if they were still useful in the exercise.

With this approach, we focused on malware analysis websites such as VirusTotal, Any.run, Hybrid Analysis… which are continually consulted by analysts to find information on samples or analyze them. The results are displayed on the web interface of these tools, showing useful information for the analysts such as IP addresses or domains to which they connect, commands executed, payloads introduced and a long list dedicated to making the life of the defenders easier.

With this information in mind, our approach was to find vulnerabilities in the web interface of these services in order to identify users. Cross-site scripting (XSS) was the perfect option for this task.

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Threat hunting (IV): hunting without leaving home. Grafiki

7 de October de 2020 Por

See first, second and third part.

Teoría de Grafos: Análisis relacional de las Redes Sociales

Today’s post covers something very special to me.

In the previous entry we saw the exploitation of information with Kibana and its usefulness in seeing potential anomalies at a glance. After a lot of work with Kibana, spending many hours creating visualizations and dashboards, there was one visualization that I missed: the graphs!

In that sense, I read some time ago the sentence “Defenders think in lists. Attackers think in graphs“.

Although it can raise a lot of controversy, if that were true it would leave us, defenders, at a clear disadvantage. In a world where threats are increasingly complex, being able to “connect the dots” makes the difference between finding our threat or not.

From this idea and an increase in my free time due to lockdown, Grafiki emerged. Let’s take a look at it.

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Business continuity: things to consider

1 de October de 2020 Por

Let’s continue with business continuity. Today I would like to review some points to be taken into account during the implementation of a Business Continuity Plan, which I consider essential to achieve a successful outcome:

1. The scope.

2. Senior management support

3. Investment

4. Setting the objective recovery times.

And with this extremely short introduction, let’s go into the matter.

1. The scope

The first aspect that we must take into account is the scope of our Business Continuity Plan (BCP), in two different areas. On the one hand, in an horizontal sense, it is necessary to clearly define which services, activities or processes are going to be included in the BCP, if we also intend to certify the management system in ISO 22301 standard. Although from a BCP’s usefulness point of view the most logical thing is to include the entire organization, especially in small companies where the infrastructure is shared for all the organization, it is also possible to choose a reduced scope that covers relatively independent elements (a local branch or the company’s headquarters, for example), or simply include those processes that are known beforehand to be the most critical for the organization’s continuity, such as production or logistics in a more industrial company, or the web portal in a purely e-commerce company.

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Cognitive bias in Threat Hunting tasks

30 de September de 2020 Por
Image by Mohamed Hassan

As any analyst knows, the very nature of Threat Hunting entails the application of generic approaches for the detection of anomalies. Unlike the reactive positions of rule-based security, proactive analysis delegates a significant percentage of detection to the analyst. This means that, as it happens to a conventional intelligence analyst, errors of interpretation tend to occur, due to the large number of casuistry found on a daily basis, and which the brain tends to classify as legitimate or malicious in hundredths of seconds.

According to Richard Heuer’s definition in “Psychology of Intelligence Analysis“, an analyst has limits in the interpretation of information, determined by his personality, his beliefs and his cognitive biases. After the identification of the anomaly, the analyst must be able to make a prediction. That is to say, it is the interpretation of a detection and its association to a possible threat that represents a security alert.

And not only this, but, as defined by Steven Rieber in his “Intelligence Analysis and Judgmental Calibration“, the analyst must also be capable of weighing the criticality of an anomaly, which also remains within subjective positions in the form of subjective probability.

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