A new spam campaign has been identified that uses Excel Web Query files to deliver malware. In this case, the .iqy files are used to launch PowerShell scripts that give the attackers root access to a device. .iqy files are not usually blocked by spam filters, making the technique effective at silently delivering malware.
The spam emails are being delivered via the Necurs botnet. Three spam campaigns have been detected by Barkly that use these attachments, although further campaigns are almost certain to be launched.
Excel Web Query files obtain data from an external source and load it to Excel. In this case, the external data is a formula which is executed in Excel. The formula is used to run PowerShell scripts which, in at least one campaign, downloads a Remote Access Trojan (RAT) called FlawedAmmyy Admin – a tweaked legitimate remote administration tool that gives the attacker full control of a computer, allowing any number of malicious programs to be installed.
The emails masquerade as purchase orders, unpaid invoices, and scanned documents – Common themes used in spam emails to deliver malware. These spam email campaigns often use Word documents with malicious macros. Macros are usually disabled by default. Through security awareness training, end users have been conditioned not to enable macros on documents from unknown senders, thus preventing malware downloads.
Since most end users will not be used to receiving .iqy files, these attachments should arouse suspicion. Microsoft has also built in warnings to prevent these files from being run by end users. If an end user attempts to open one of these files it will trigger a warning alerting the user that the file may not be safe as it enables an external connection. The end user would be required to click enable before the connection is made and data is pulled into Excel. A second warning would then be displayed, again requiring authorization. Only if both warnings are ignored will the script be allowed to run that downloads the malicious payload.
There are two steps you can take to protect your endpoints and networks from these types of attacks. The first is to configure your email spam filter to quarantine any emails containing .iqy attachments. SpamTitan allows certain attachment types to be blocked such as executable files and iqy files. You can set the policy to quarantine, reject, or delete the emails. Since these types of files are not usually sent via email, rejecting the messages or deleting them is the safest option.
You should also cover the use of these files in your security awareness training sessions and should consider sending an email alert to end users warning them about the threat.
Further information on steps you can take to prevent malware infections spread via email can be found in our anti-spam tips page. You can find out more about the capabilities of SpamTitan by calling the sales team:
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