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How Hiring Employees Increases Your Chance of a Ransomware Attack

How Hiring Employees Increases Your Chance of a Ransomware Attack

Tips For Avoiding Ransomware Attacks

It seems like a strange combination, employee hiring and Ransomware but there is a connection. Ransomware is one of the biggest network security issues in today’s world and businesses have paid out tens of millions in ransoms this year. Thankfully a lot more people are aware of the problems it can cause and how it can get into a network. This is making things more difficult for the virus writers but they are a resourceful bunch with a lot of time on their hands.

Most people avoid opening attachments in emails from strangers. However, there are ways to trick people into opening attachments with virus payloads.

One such way which I observed recently is where companies advertise for new job positions. A common approach is to advertise jobs on websites and make a bit of noise about it on social media. Contact details are usually published and people submit their applications.

What we now have is strangers sending their CV’s as attachments and this introduces a new attack vector as it is not seen as unusual activity. Malicious attachments really have made a comeback as top attack vector.

Ransomware bandits know that sending email to a generic human resources email address may not be successful as HR teams will be used to dealing with attachments. They will employ social engineering tactics and send their ‘CV’ to other email addresses within the company. The helpful recipient will probably forward it on and may even open it. As soon as they do they will find their files are encrypted.

Attack Surface

Advertisements for jobs and other services within a company increases that companies attack surface.

These social engineering attacks are getting more and more advanced. Not that long ago you could spot the suspicious emails easily as they contained lots of spelling mistakes or started off with something like “Dear Firstname”. This is no longer the case, one off emails are written for specific attacks and they can look legitimate at first glance. You should also be on the guard for unsolicited messages in LinkedIn and other social networks.

Anatomy of a Ransomware Attack

Anatomy of a Ransomware Attack

  1. Attacker spots company activity. Job announcements, corporate events, etc…
  2. Email created to match company activity
  3. Email sent to unsuspecting employees with attachment
  4. Attachments opened, files encrypted locally and on shared drives

Tips For Preventing Ransomware Attacks

The lessons here of course are to continue to educate employees on the dangers of opening emails from strangers. Perform spot checks by creating a new Gmail address and send emails to see if employees open them or forward them on to others.

Email attachment with virus
Do we really need email attachments in the era of cloud based applications?

As well as sending in bogus CV’s you will see tactics such as sending bogus purchase orders, software licenses, delivery notices and banking statements. In most cases the email will be tailored to match the recipients role or to coincide with specific company events.

I am beginning to wonder in the age of cloud applications, do we really need to be sending attachments in emails? They have been the source of countless virus outbreaks over the years. For example, the ILOVEYOU virus from a few years ago affected over 45 million computers.

Employee training and security awareness is the number one way you will prevent Ransomware attacks. In parallel to this you should make sure you have some sort of network monitoring tool in place that can track who is accessing file shares and give you warnings when something suspicious is happening. Also consider:

  • Block attachments on emails or restrict them to specific accounts.
  • Use contact forms on your website instead of publishing email addresses.
  • If you use Google Apps check out the attachment filtering feature. It lets you block specific attachment types or quarantine them for review later.

The image below shows a sample SMTP email report from NetFort LANGuardian which shows suspicious looking attachments that were detected moving around on a network. This information was captured using Wire Data Analytics. Two things look strange from this. Firstly the same email was sent to two people and secondly the compressed attachment (zip) is a tactic used to try and get past email filters.

New variants of Ransomware are appearing on a daily basis. Do not rely on host based antivirus as they struggle to keep up. Training and constant monitoring are the most vital activities and don’ forget about your backups.

Dealing With A Ransomware Attack

I would recommend that you create an incident response document before you get hit by Ransomware. Just something basic like backup information, support contact details, what tools to use for forensics etc… Also include notes on shutdown steps for key servers and applications.

If you do get hit, don’t just pay the ransom. As soon as you have it paid you will be dealing with another outbreak. Watch out for infected files on cloud storage services such as DropBox, files encrypted or infected with malware could be synchronized with a cloud service within seconds. It is a good example of why should really know what applications your users are running on your network. We have a few other blog posts which you may find useful in the event of a Ransomware outbreak.

The following video also shows how you can use file activity logs to track down the source of Ransomware on a network

I cannot stress how important training is for the prevention of network security attacks. If you make noise about something within your company like job postings, financial updates or corporate events, be prepared for advanced social engineering attacks.

Do you have any experiences with Ransomware attacks? Comments welcome

Darragh Delaney