Targeted email attacks (called spear phishing) with harmful links or attachments containing malware are an ever-increasing threat. These attacks are part social networking and part sophisticated technical effort to penetrate companies' defense systems. Traditional security deployments, in many cases, aren't prepared for these kinds of attacks.
The weakest link of any network is the user. But it's not always their fault. If a person receives an email from a real co-worker with a link, how can that person know the link will send them to a zero-day threat or that the attachment is a CryptoLocker attack?
After you train your users, they will have a good amount of fear and how-to ideas in mind, but over time they will forget or get sloppy -- and it takes only one or two clicks to pull CryptoLocker or similar threats into your environment. CryptoLocker is especially insidious malware because it encrypts all files -- documents, databases, photos, and so on -- with military-grade encryption unless you pay a ransom. Also, there is only one key to decrypt -- and the attacker is holding and asking money for it. Overall, ransomware is getting smarter.
You need to look at putting protections in place that checks links and scans email for malware as standard.
It's easy enough to scan email as it comes in and look for known viruses and such. What's hard is thwarting the kinds of sophisticated attacks where truly devastating tools like CryptoLocker are used: Someone sends a link that, at the time it comes through, points to a legitimate and safe server. But later, that link is switched by the attacker on the server side to a harmful location. There is typically no recheck in place when a user clicks a link in their email.
There should be -- and there can be.
You need email protection that covers the full lifecycle of a message, for as long as that message exists and there is a link to be clicked, when clicked the system will ensure the URL is still pointing to a safe location.
Tools for lifecycle malware detection carry different names, including targeted threat protection (TTP), targeted attack protection (TAP), and click-time link scanning. Whatever you call it, you want it in place.
You also want to scan all your systems and data stores to see if anything has already snuck through and is lurking to cause damage later. You have plenty of tools to do that, such as Malwarebytes Antio-Malware, which is what I use.
What happens if you are infected by ransomware? You have two options:
- Pay the ransom and get back to work
- Restore from backup, assuming it wasn't infected too
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