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CrypVault

Posted: April 8, 2015

Threat Metric

Threat Level: 10/10
Infected PCs: 35
First Seen: April 8, 2015
OS(es) Affected: Windows

CrypVault is a file encrypting Trojan that also incorporates spyware add-ons capable of collecting information, such as your account login. While CrypVault has seen the greatest rates of distribution in Russia and neighboring countries, CrypVault also has begun to be seen in meaningful numbers elsewhere, including North America. During its attacks, CrypVault portrays itself as a legitimate PC security tool for recovering locked files. However, malware researchers see no advantages in victims paying its ransom and recommend responding to CrypVault as threatening software, with appropriate security tools.

The Vault where Your Files go to Die

CrypVault distributes itself through disguised e-mail attachments, with the attached file using threatening, hidden JavaScript content to trigger its Trojan dropper. The primary threat installed, CrypVault (or BAT_CRYPVAULT.A), conceals the bulk of its files in the user's temporary files folder. Although CrypVault avoids files with specific text labels, such as 'games' or 'adobe', CrypVault encrypts most other files on a list of given types. Formats preferred by CrypVault for encryption include DOC, XLS, JPG, and ZIP. Encrypted files acquire a .vault name extension, implying that the data in question has been compromised and, thus, quarantined for your protection. File icons also are changed.

PC users trying to access their encrypted files will experience a pop-up warning, which claims that CrypVault has placed them in a 'vault' unlocked via a unique key. This key supposedly is accessible from an address navigated from within the Tor Browser. The Tor Browser, also used by other threats like Critoni and OnionDuke, provides theoretically anonymous Web-surfing, which hackers prefer for illicit cash transactions. A second pop-up image and text notification will automatically load when Windows starts, along with the rest of CrypVault.

Protecting Your PC's Data from a Self-Destructive Quarantine

CrypVault should clearly be distinguishable as being threatening software, rather than a legitimate security application, despite its use of file protection terminology similar to those of real anti-malware products. Purchasing the key for unlocking your files does not necessarily provide any way of restoring your encrypted information. However, malware experts also found that CrypVault uses a third-party utility, SDelete, to block other attempts at file recovery. In such cases, keeping additional, remote file backups on uninfected drives, such as a USB device, is a practical way of protecting your PC's contents cheaply.

As a secondary warning, malware experts also have associated CrypVault with some spyware attacks related to collecting browser passwords. This attack uses yet another third-party app, which, like SDelete, is not threatening. PC users recovering from CrypVault infections should strongly consider making appropriate changes to all important passwords used for their online accounts.

CrypVault may be a Trojan with multiple capabilities, but also is a relatively primitive one. Its use of batch scripts in lieu of 'real' programming language makes its functionality limited, but also easy to develop and apply to future campaigns. Finally, while competent anti-malware products should have no issues with detecting and removing CrypVault, you also may need to take extra steps for deleting its secondary, non-threatening applications.

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