OPM-Impersonating Spam Emails Distribute Locky Ransomware

A newly observed spam email campaign appears to be preying on last year’s US Office of Personnel Management (OPM) breach incident to distribute the Locky ransomware, PhishMe researchers warn.

Ever since Locky first emerged in February this year, the actors behind it have been actively switching between different distribution methods to avoid detection. Not only did they use various attachment types in spam emails, such as macro-enabled Office documents, JavaScript, DLLs, and Windows Script Files (WSF), but they also changed the extension appended to encrypted files from .locky to .zepto and then .odin.

Recently, Locky’s operators decided to impersonate the US Office of Personnel Management in a new distribution campaign. 

The messages distributed as part of this spam campaign claim alleged “suspicious movements” in the victim’s bank account, supposedly detected by OPM. The emails come with a ZIP archive attached, with JavaScript code packed inside. The JavaScript is meant to download and run the Locky ransomware, similar to many other distribution campaigns.

According to PhishMe, because the emails in this campaign appear to have been sent by the OPM, they are likely to trick government workers and employees of government contractors. Moreover, they are also highly likely to appeal to individuals who have been impacted by last year’s high-profile OPM breach.

Overall, 323 unique JavaScript application attachments were identified as part of this campaign, and they were used to download Locky from 78 distinct payload locations.

What the security researchers also point out, however, is that the spam campaign would not stand up if the OPM reference was missing from it. If said reference is removed, these would be just another set of phishing emails using “suspicious movements” and “out account” word combinations to distribute the Locky ransomware.

Also of importance is the fact that there’s no indication that Locky’s authors were targeting people impacted by last year’s breach. What’s more, the security firm says that it has no reason to believe that government employees were specifically targeted as part of a spear phishing attack. In fact, many people who weren’t impacted by the hack and who aren’t affiliated with the U.S. government also received these spam messages.

“The email addresses associated with the OPM breach have not been actively circulated.  As such, it is incredibly unlikely that the threat actors have any detailed knowledge of who will be receiving these emails. Furthermore, PhishMe has not received any confirmation that anyone impacted by the OPM incident has received a copy of these emails,” the security company says.

Related: Researchers Build Configuration Extractor for Locky Ransomware

Related: Leadership, Not Technology, Blamed for Huge OPM Breach