Security Experts:

Targeted Attacks Leverage PowerPoint File for Malware Delivery

Threat actors are leveraging malicious PowerPoint files and a recently patched Microsoft Office vulnerability to target UN agencies, foreign ministries, international organizations, and entities interacting with international governments, Fortinet warns.

The attack uses a file named ADVANCED DIPLOMATIC PROTOCOL AND ETIQUETTE SUMMIT.ppsx and exploits the CVE-2017-0199 vulnerability that Microsoft addressed in April, after malicious actors had been abusing it to deliver malware such as Dridex, WingBird, Latentbot and Godzilla. The exploit has been and continues to be used in attacks even after patching.

Last month, the first PowerPoint attacks to exploit CVE-2017-0199 for malware delivery emerged, associated with the distribution of a Trojanized version of the REMCOS legitimate and customizable remote access tool (RAT).

Once the PowerPoint Slide Show is opened, it triggers a script and the exploit downloads remote code from an XML file with JavaScript code from the domain narrowbabwe[.]net. Next, it executes the code using the PowerPoint Show animations feature, Fortinet explains.

The exploit is also able to bypass the User Account Control feature in Windows, by hijacking the registry and then executing eventvwr.exe. The bypass technique was first detailed in August 2016.

The JavaScript inside the XML file would write a file in a directory, masquerading as a legitimate Microsoft Office patch. This, however, is a piece of malware executed with high privilege, which uses WMI ActiveScriptConsumers for persistence. Courtesy of a timer event, the script runs every 12 seconds.

The script also tries to identify if it runs in a virtual environment. If it doesn’t detect a virtual machine, the script proceeds to sending some data to a remote server.

Although the command and control (C&C) server had been already taken down at the time of analysis, the researchers say that the response from the C&C contains arbitrary commands executed with eval() function. After executing the commands the script sends a notification to the server.

“These commands can possibly be download functions to deliver the final payload, and the most commonly used malware for espionage are RATs (Remote Access Trojans),” Fortinet suggests.

Last month, Cisco discovered that attackers were combining Office exploits to avoid detection and ensure higher delivery rate. Fortinet’s new report shows that actors can implement multiple techniques in a single piece of code to evade detection, bypass protections, and escalate privilege. The use of multiple embedded encoded scripts, multiple stages of URL connection, and the embedding of C&C URLs in a jpg file reveal the work of persistent criminals.

Related: Attackers Combine Office Exploits to Avoid Detection

Related: PowerPoint Slide Show Files Used to Install Malware

Related: Office 0-Day Abused in Latentbot, WingBird Attacks

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