Critical Office Zero-Day Attacks Detected in the Wild

At McAfee, we have put significant efforts in hunting attacks such as advanced persistent threats and “zero days.” Yesterday, we observed suspicious activities from some samples. After quick but in-depth research, this morning we have confirmed these samples are exploiting a vulnerability in Microsoft Windows and Office that is not yet patched.

This blog post serves as a heads-up for our customers and all Office users to protect against this zero-day attack.

The samples we have detected are organized as Word files (more specially, RTF files with “.doc” extension name). The exploit works on all Microsoft Office versions, including the latest Office 2016 running on Windows 10. The earliest attack we have seen dates to late January.

The exploit connects to a remote server (controlled by the attacker), downloads a file that contains HTML application content, and executes it as an .hta file. Because .hta is executable, the attacker gains full code execution on the victim’s machine. Thus, this is a logical bug, and gives the attackers the power to bypass any memory-based mitigations developed by Microsoft. The following is a part of the communications we captured:

The .hta content is disguised as a normal RTF file to evade security products, but we can find the malicious Visual Basic scripts in a later part of the file:







The successful exploit closes the bait Word document, and pops up a fake one to show the victim. In the background, the malware has already been stealthily installed on the victim’s system.

The root cause of the zero-day vulnerability is related to the Windows Object Linking and Embedding (OLE), an important feature of Office. (Check our Black Hat USA 2015 presentation, in which we examine the attack surface of this feature.)

We strongly suggest Office users take the following actions to protect or mitigate against this zero-day attack before Microsoft issues an official patch. We notified the Microsoft Security Response Center as soon as we found the suspicious samples, and we will continue to work with them to protect Office users.

  •  Do not open any Office files obtained from untrusted locations.
  •  According to our tests, this active attack cannot bypass the Office Protected View, so we suggest everyone ensure that Office Protected View is enabled.

We will continue to update our findings on this ongoing investigation.


Special thanks to Bing Sun, Chong Xu, Christiaan Beek, and Abhishek Karnik (and his team) for their help with this investigation.

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Leveraging SIEM and Security Analytics for Improved Monitoring of Advanced Threats

For more than a decade, in response to higher volumes of alerts, security information and event monitoring (SIEM) became an integral component of enterprise security programs. However, the increasing sophistication and complexity of attacks are driving the need for advanced analytics—beyond the log aggregation of older SIEM solutions. Security analytics, which uses Big Data technologies, has emerged to fill in the gaps.

In its recent report, “Security Analytics Team of Rivals,” consulting firm Securosis contends that security analytics solutions provide maximum value when integrated with advanced SIEM solutions and vice versa. One is not a replacement for the other, nor should they be viewed as competing solutions.

Most enterprises have had a SIEM in place for a number of years. Its main strengths include: data aggregation, correlation, forensics and incident response, and reporting. The data sets that are generally handled best by a SIEM are network data, endpoint activity, server and data logs and change control activity, identity data, application logs, and threat intelligence feeds.

One thing that some SIEMs struggle with is finding patterns in large volumes of data. Security analytics solutions, on the other hand, are intentionally designed to crunch through SIEM’s huge data sets, looking for indicators of malicious activity, such as anomalous patterns of activity, misconfiguration, or privilege escalation. The integrated solutions are particularly good at advanced threat detection and tracing insider attacks.

How do you benefit from integrating analytics solutions with your SIEM? For one thing, today’s security analytics solutions don’t allow you to search for an alert and then set in motion an incident response process—SIEMs handle that job and lend themselves well to easy and comprehensive threat activity visualizations and reporting. There are two key integration points where you’ll find the combination invaluable:

  • Automated Data Analysis: SIEMs have been proficient at collecting and aggregating data for a long time. In order to extract this data for further analysis, ensure that your integration of SIEM and security analytics has sufficiently robust automated processes. This can save an enormous amount of time.
  • Alert Prioritization: Both your SIEM and your security analytics tools will create and send out alerts. Bi-directional information sharing between the SIEM and security analytics solutions is essential so that your team can prioritize investigative actions and maintain context.

Let’s look at a scenario where SIEM and security analytics can complement one another to detect what appears to be an advanced insider attack. In this use case, the security team of a fast-growing retail operation receives an alert from its SIEM solution. It appears that an insider is probing the internal network, which is highly unusual activity for an employee. For a more complete picture of the situation, the team accesses its integrated SIEM and security analytics solution for additional insights on what the adversary is up to. The integrated investigation reveals several types of unusual activity—like privilege escalations and configuration changes on multiple devices. The SIEM reports the trajectory of the attacker, which results in compromise of the device that triggered the alert in the first place, and this enables smarter and faster remediation.

To learn more about how your SIEM and security analytics tool can coordinate and complement each other, read the Securosis report, “Security Analytics Team of Rivals.”

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