Following on from a supply chain attack that saw the software update feature of the Passwordstate password manager hijacked the threat group developed a convincing phishing campaign targeting enterprise users of the password manager solution.
The supply chain attack was used to infect users of the password manager with malware dubbed Moserpass. Between April 20 and April 22, users of the password manager who downloaded an update through the In-Pass Upgrade mechanism may have had a malicious file downloaded – a malformed Passwordstate_upgrade.zip file.
Downloading the file started a chain of events that resulted in Moserpass being installed, which collected and exfiltrated information about the computer, users, domains, running services and processes, along with password data from the Passwordstate app. The malware also had a loader module, so could potentially download other malware variants onto victims’ devices. Since passwords were potentially compromised, affected users have been advised to reset all of their passwords.
The attack only lasted 28 hours before it was identified and blocked, but in order to remove the malware from customers’ devices, Click Studios, the developer of the password app, emailed customers and encouraged them to apply a hotfix to remove the malware.
Some customers who received the email from Click Studios shared a copy of the message on social media networks. The threat group behind the attack were monitoring social media channels, obtained a copy of the genuine Click Studios email about the hotfix, and used the exact same email for a phishing campaign. Instead of directing users to the hotfix to remove Moserpass malware, the phishing email directed users to a website not under the control of Click Studios which installed an updated version of Moserpass malware.
Since the Passswordstate breach notification emails were virtual carbon copies of genuine communications from Click Studios they were very convincing. Users who followed the instructions in the email would likely think they were removing malware, when they were actually installing it. The fake versions of the emails do not have a domain suffix used by Click Studios, request the hotfix is downloaded from a subdomain, and claim an ‘urgent’ update is required to fix a bug, but it is easy to see how these messages could fool end users.
Click Studios supplies its password manager to around 29,000 enterprises and the solution has hundreds of thousands of users, many of whom will have heard of the breach and be concerned about a malware infection. Click Studios said only a very small number of its customers were affected and had the malware installed – those who downloaded the update in the 28-hour period between April 20 and April 22 – but anyone receiving the fake email could well have been convinced that the email was genuine and taken the requested action.
Phishers often use fake security warnings as a lure, and data breach notifications are ideal for use in phishing attacks. This Passswordstate breach notification phishing campaign highlights the importance of carefully checking any message for signs of phishing, even if the email content seems genuine and the message includes the right branding, and the risks of posting copies of genuine breach notification letters on social media networks.
Many phishing attacks are sophisticated, and it can be difficult for employees to differential between genuine and malicious messages, which is why advanced spam and phishing defenses are required. If you want to improve your defenses against phishing, get in touch with TitanHQ and discover how SpamTitan Email Security can improve your security posture and better protect your organization from phishing and other email-based threats.