A particularly nasty new threat has emerged: Spider ransomware. The new crypto-ransomware variant was discovered by security researchers at Netskope on December 10, and the campaign is ongoing.
While many ransomware variants give victims a week to make contact and pay the ransom, the actors behind Spider ransomware are far less patient. If the ransom payment is not made within 96 hours of infection, the key to unlock files will be blocked and files will be permanently encrypted. Further, victims are warned “do not try anything stupid, the program has several security measures to delete all your files and cause damage to your PC.”
Naturally, that something stupid is not attempting to recover files from backups. If viable backups exist, victims will be able to recover their files without paying the ransom, but the warning may put off some victims from trying.
Such a short window for payment does not give victims much time. Many ransomware attacks occur on a Friday, and are only discovered when employees return to work on a Monday. Discovering a Spider ransomware attack in this scenario means businesses will have to act particularly quickly in order to avoid file loss.
While the threat is severe, the attackers have made it as easy as possible for victims to pay by providing a detailed help section. Payment must be made in Bitcoin via the Tor browser and detailed instructions are provided. The attackers say in the ransom note, “This all may seem complicated to you, actually it’s really easy.” They even provide a video tutorial showing victims how to pay the ransom and unlock their files. They also point out that the process of unlocking files is similarly easy. Pasting the encryption key and clicking on a button to start the decryption process is all that is required.
As with the majority of crypto-ransomware variants, Spider ransomware is being distributed by spam email. The emails use the hook of ‘Debt Collection’ to encourage recipients of the email to open the attachment. That attachment is a Microsoft Office document containing an obfuscated macro. If allowed to run, the macro will trigger the download of the malicious payload via a PowerShell script.
The latest Spider ransomware campaign is being used to attack organizations in Croatia and Bosnia and Herzegovina, with the ransom note and instructions written in Croatian and English. It is possible that attacks will spread to other geographical areas.
There is currently no free decryptor for spider ransomware. Protecting against this latest ransomware threat requires technological solutions to block the attack vector. If spam emails are not delivered to end user’s inboxes, the threat is mitigated.
Using an advanced cloud-based anti-spam service such as SpamTitan is strongly advisable. SpamTitan blocks more than 99.9% of spam emails ensuring malicious email messages are not delivered.
As an additional protection against ransomware and malware threats such as this, organizations should disable macros to prevent them from running automatically if a malicious attachment is opened. IT teams should also enable the ‘view known file extensions’ option on Windows PCs to prevent attacks using double file extensions.
End users should also receive security awareness training to teach them not to engage in risky behaviors. They should be taught never to enable macros on emailed documents, told how to recognize a phishing or ransomware emails, and instructed to forward messages on to the security team if they are received. This will allow spam filter rules to be updated and the threat to be mitigated.
It is also essential for regular backups to be performed, with multiple copies stored on at least two different media, with one copy kept on an air-gapped device. Backups are the only way of recovering from most ransomware attacks without paying the ransom.