applied security research
Rik van Duijn - 26 mei 2020

Phishing aftercare

This blog is part of our Office 365 attack & defense series. We also maintain a Github page where we share our Office 365 tools and queries. We often get sent phishing emails by family and friends. Not to phish us but because we ask family and friends to forward them to us. Sometimes they also send them to ask us for a second opinion. For us its an interesting insight into what people get sent and sometimes the start of a fun research project. Usually these phishing attempts are a standard and untargeted, sometimes they are clearly an internal phishing test. If a message seems targeted towards a person or organization we always advise them to contact internal IT administration or security departments. Unfortunately people often do not respond positively to this advice. Submitting the message is too complex and there is no feedback whether or not it was malicious.

Handling user-reports

Recently we got another message: “Hey is this right?” including a screenshot of an email. The email described the email storage quota was exceeded. And in the attachments a word document with the instructions on how to fix the quota. The email message used the organization name and so did the filename of the word document. It’s still unclear if this is a phishing test by the organization or an actual phishing attempt. We used this phishing scenario in the past so it did feel like phishing but in the end it didn’t feel right. So I advised to contact their IT department. The immediate response was they didn’t want to do so: the last phishing message they forwarded, returned a snarky response stating they didn’t follow proper procedure. Which is unfortunate: as a defender getting these messages from our colleagues helps us to detect threats. Recently the university of Maastricht was hacked and ransomed. The initial vector: phishing. phishing. Awareness and reporting on its own is obviously not enough but making sure everyone reports if they see something suspicious will help. Next to making it easy to report users need to receive feedback of their report. If someone feels they are contributing they will be more willing to send them in.

Helping users report phishing

Having a quick and easy procedure to receive the messages is important. But we need the original message so we could instruct users to only forward as attachment. But this is not a button that is in the main screen and would require users to click around. As IT we sometimes forget that an employee is not there to act as a human spam filter. So that notification should be made as simple as possible. It is easy for office365 and exchange users to receive notification from users. A user can classify an email as spam or phishing in the web interface. Normally all email will go directly to Microsoft. But it is also possible to receive it yourself. A mail flow rule allows the messages sent to Microsoft to be bcc-ourselves. Now suppose you don’t want Microsoft to receive these messages, you can also choose to redirect the message instead of sending a bcc. How to do this is at the bottom of the article. Technically not very complicated to receive a phishing report. Now it remains for us to inform our colleagues how to report. And providing feedback and the latter can be difficult. Not every report is relevant at all and, depending on the size of the organization, it does not scale to respond 1-on-1. An option could be to include something like this in the newsletter or to raffle something cool under the best phishing submission. It doesn’t really matter, as long as you show that you do something with it!

Configure mailflow:

Setting up the mail flow rule can be done in 2 ways, via the GUI and via powershell.

Via the GUI

  1. Log in to the Exchange Admin center
  2. Select “email flow”
  3. Select “rules”
  4. Create a new rule with the following properties:
* the Redirect To options will make sure the Phishing email is not send to Microsoft but to you instead.

PowerShell FTW:

What can be done by hand is easier with PowerShell, replace -BlindCopyTo with -RedirectMessageTo if you don’t want these messages to be sent to Microsoft. The script is also available in our Github repository:

#Modify email adress and rule name below: 
$recipient = "YOUREMAILADRESS"
$name = "[ZOLDER] Recieve user alerts"

New-TransportRule $name -SentTo "[email protected]","[email protected]","[email protected]" -BlindCopyTo $recipient -StopRuleProcessing $false -Mode "Enforce" -Comment "" -RuleErrorAction "Ignore" -SenderAddressLocation "Header"


You can add text or html to any email from outside of the company. This allows you to add a warning to emails from external sources. Which could help users identify false messages. We’ve added the script to our Github repository, use it to add this to your o365 environment. You can add your own organisation name, the layout looks like this: Don’t forget to inform users of this change, if they know it’ll be added they will be better prepared to use it.

Internetoplichters richten pijlen op Hockeyvereniging

Erik Remmelzwaal - 10 mrt 2023
De penningmeester van Hockeyclub Zevenbergen ontving een poging tot oplichting. Gelukkig werd het herkend, maar zal dat overal gebeuren, nu internetoplichters hun pijlen blijkbaar op sportverenigingen hebben gericht? Lees verder

Microsoft Digital Defense Report

Erik Remmelzwaal - 14 nov 2022
Het Digital Defense Report 2022 van Microsoft is uitgekomen. Wat zijn de highlights en key takeaways? Lees verder

TBX2022 Throwback & Masterclass

Erik Remmelzwaal - 07 nov 2022
Op 2 en 3 november vond in de Jaarbeurs Utrecht de TBX2022 beurs plaats. Zolder was net als vorig jaar aanwezig als exposant, en was op beide dagen de host van een masterclass. Ons voornaamste doel was om ons nieuwe propositie van Attic for MSPs bekend te maken. Met deze nieuwe release, stellen we andere […] Lees verder

Hacking my Helium Crypto Miner

Wesley Neelen - 05 sep 2022
Recently I came across an interesting cryptocurrency project called Helium. Its a wireless network built by people all around the world. The people that help expanding the network by adding a hotspot receive the Helium cryptocurrency coin by providing the coverage. During my research I decided to order one of those Helium miners. I ordered […] Lees verder

PEN-300 / OSEP review

Wesley Neelen - 19 jul 2022
This year I decided to start a new study, the PEN-300 course of Offensive Security. In 2012 I did the OSCP course and in 2013 OSCE. In 2016 I took the OSEE class in Vegas, unfortunately never took the exam (one of my biggest mistakes ever🥴). I liked all the courses very much at that […] Lees verder

Deze 3 misverstanden blokkeren het ontwikkelen van cyberweerbaarheid

Zolder B.V. - 04 jul 2022
Het NCTV heeft weer het jaarlijkse Cybersecuritybeeld Nederland gepubliceerd. Het CSBN-2022. Mooie aanleiding om eens op te schrijven waar ik al langer mee in mijn hoofd zit. Drie hardnekkige en foute aannames die mensen hebben bij digitale dreigingen. Drie misverstanden dus, die in mijn ervaring de belangrijkste reden zijn dat we nauwelijks vooruit komen met […] Lees verder

Cyberweerbaarheid en Operational Technology

Erik Remmelzwaal - 02 jun 2022
Onlangs nam Erik Remmelzwaal, co-owner en Managing Director van Zolder BV, deel aan een tafelgesprek van Data Value Center – Smart Industry (DVC-SI). Het thema was Cyberweerbaarheid en Operational Technology, en het gesprek werd opgenomen in de campus van Breda Robotics, waar Zolder lid van is. De opname is inmiddels beschikbaar en terug te kijken […] Lees verder

Detecting MFASweep using Azure Sentinel

Zolder B.V. - 01 nov 2021
Many companies are using cloud services such as Microsoft 365 for email, file sharing and communicating. If an attacker gains access to valid credentials that allows them to authenticate to the account, all information within the account is usually instantly accessible. Therefor, implementing multi factor authentication is one of the most important steps while securing […] Lees verder

Public SharePoint sites - the new open shares

Wesley Neelen - 16 sep 2021
During one of our engagements we were investigating a Microsoft 365 environment. My colleague Rik discovered that many SharePoint sites were publicly available within the organization. We were surprised by the amount sites that were wide open this way. A lot of sensitive information was located on those sites, for example PII-information and passwords for […] Lees verder

Decrypt passwords from Xerox Workcentre config backups

Rik van Duijn - 29 aug 2021
During a recent engagement we encountered Xerox WorkCentre printers using default credentials (admin:1111). Usually it’s just another finding, but this time we noticed the printer had SMB and e-mail credentials configured. For LDAP we usually point the printer to our own IP and get access to the plaintext creds that way. But in the case […] Lees verder

Office 365 audit logging

Rik van Duijn - 19 aug 2021
It’s important to enable audit logging for o365 even if you are not monitoring them actively. Atleast if you get hacked there’s logging to investigate :). The audit log is not always enabled by default, it seems to rely on license levels. However there are some important things to take into consideration. You can enable […] Lees verder

Ransomware, nationale crisis?

Erik Remmelzwaal - 04 aug 2021
Als er 1 digitale dreiging is die veel in het nieuws komt, dan is het ransomware. Er wordt zelfs gesproken van een nationale crisis. Lees verder

Mijlpalen en hoe het gaat

Zolder B.V. - 02 jul 2021
Vandaag gebeurden er op Zolder toch een paar dingen die blogwaardig zijn. Dus prima aanleiding om nog maar eens de laptop open te klappen en te vertellen hoe het gaat. Nieuwe collega’s Het is 1 juli 2021 en we zijn ruim een jaartje onderweg als Zolder. De belangrijkste stap die we vandaag zetten, is dat […] Lees verder

Zolder wordt hoofdsponsor HCZ

Zolder B.V. - 01 jul 2021
Vandaag is bekend geworden dat Zolder de nieuwe hoofdsponsor is van HCZ – Hockeyclub Zevenbergen. De komende drie seizoenen zal het logo van Zolder daarom voorop de shirts van alle HCZ leden prijken. We zijn heel erg trots op deze nieuwe stap voor ons jonge bedrijf, en hopen zo de relatie met onze regio te […] Lees verder

Breda Robotics

Erik Remmelzwaal - 10 mei 2021
Zolder BV is toegetreden tot het netwerk van Breda Robotics. Deze vereniging brengt organisaties bij elkaar die actief zijn rondom robotisering in de regio West-Brabant. Voor Zolder geeft Breda Robotics de mogelijkheid om samen te werken met de robotiseringsindustrie. Te begrijpen hoe die sector precies werk en op welke vlakken cybersecurity kennis kan worden ingezet […] Lees verder

27% .nl domeinen slecht beschermd tegen spoofing

Erik Remmelzwaal - 29 apr 2021
TLDR: We scanden de DNS records van 1,6 miljoen .nl domeinen en vonden uit: 9% is rechtstreeks gekoppeld aan Microsoft 365, daarmee is Microsoft veruit de grootste Google is nr2 en heeft 4% van de domeinen aan zich verbonden, nagenoeg gelijk aan een aantal andere spelers. Van alle mail-enabled domeinen heeft 27% geen SPF record […] Lees verder

Zolder biedt MKB betaalbare en eenvoudige security-app

Zolder B.V. - 12 apr 2021
“Attic voorkomt dat security een luchtbel wordt” Security is bij mkb-bedrijven vaak het ondergeschoven kindje. Ze hebben er de mensen en het budget niet voor. Dat maakt deze doelgroep een aantrekkelijk doelwit voor cybercriminelen. Voor de vier doorgewinterde cybersecurity-experts van start-up Zolder reden om Attic te introduceren. Deze eenvoudige, goedkope en toekomstbestendige app maakt mkb’ers […] Lees verder

Nieuwe Themesong voor Zoldersessions

Erik Remmelzwaal - 13 mrt 2021
Ik vond het tijd worden voor een nieuw liedje voor onze Zoldersessions. Tot nu toe hadden we er een rechtenvrij liedje onder staan, namelijk EVA_失望した, maar wilden toch iets meer 'eigens'. Daar schakelden we Bjørgen van Essen voor in met dit eindresultaat. Dit is hoe dat tot stand kwam. Lees verder

Zolder.App Open Beta

Zolder B.V. - 02 feb 2021
We launched the final beta release to the Google and Apple appstores. Any business running on Microsoft 365 is more than welcome to join. As a beta-tester you will receive a free subscription to the Zolder.App Premium Plan for the remainder of the beta phase, which is scheduled to run through April 30th 2021. Zolder.App […] Lees verder

GGD data is topje van ijsberg

Erik Remmelzwaal - 26 jan 2021
Maandag kwam RTL Nieuws, na onderzoek van Daniël Verlaan, naar buiten met het nieuws dat gestolen data van de GGD online wordt verhandeld door criminelen. Het gaat om data die onderdeel uitmaakt van het bron- en contactonderzoek dat de GGD uitvoert als onderdeel van de bestrijding van Corona/COVID-19. De data bevat gevoelige persoonsgegevens en criminelen […] Lees verder