Welcome!

Cloud Security Authors: Derek Weeks, Lori MacVittie, Elizabeth White, Ed Featherston, Liz McMillan

Related Topics: Cloud Security

Cloud Security: Blog Post

Malware Delivery – Understanding Multiple Stage Malware

How trusted file attachments has opened the vector for continued intrusions.

To some of us, seeing an email with malware embedded in a PDF, Word or Excel attachment is common. In fact, it has become the new norm for malware delivery to use file types that are not obviously malicious (versus something like a .exe). Gone are the days of wide-open acceptance of all file extensions for attachments within an email. In today's network defense-in-depth techniques, one of the layers is naturally email security. This includes the scrutinizing of emails for embedded links or attachments that could be potentially malicious, scanning attachments for possible detectable viruses and even inspecting the mail header for details that could point to the continued use of a particular "sender" address targeting an organization.

With the delivery of the malware always evolving to avoid being detected, why is it so common to see multi-stage malware? What exactly IS multi-stage malware, and why can it be more difficult to detect through common defense-in-depth strategies? I recently sat with a customer who ran these questions by me.  They were concerned that this might be some kind of new and sophisticated attack being used against their organization that their security team was not aware of. Truth is, this type of attack method is more common than you know, and has been going on for a significant period of time.

Let's start by tackling the easiest questions.

Question: What is multi-stage malware?

Answer: It is malware that is delivered in stages.  Seriously, that's it.

Question: So then what are the stages?

Answer: Ah, I was hoping that was your next question...

The typical stages for the delivery are as follows;

Stage 1: The main goal of the first stage is to simply get some kind of execution on a victim computer to retrieve the larger portion of the malware.  Utilizing a legitimate looking file (PDF, DOC, XLS) that is embedded with the stage 1 malware, the attacker can entice the target to open it, and allow execution. After execution, the first stage malware may also find some way to make itself persistent. What do I mean by persistent? Well let's say that as soon as you open an infected PDF, the stage 1 malware begins execution on your computer, but you happen to immediately shut down your computer.  If that malware did not create some kind of way to re-execute after you start your computer, it will not execute again until you open the infected PDF again. Attackers know that it's unlikely you will re-open the attachment, so they like to build in a way for the malware to re-execute after your computer starts up.  That way it is guaranteed to finish its initial job, which is to retrieve the next stage malware.

Stage2: This is where the more robust malware sections of the malware are introduced, potentially causing an unfettered amount of damage to its victim computer. Stage 2 typically gives the attacker an array of capabilities that are not available with stage 1, such as:

  • Victim computer screen capture
  • Start webcam
  • Graphical ability to browse victim computer file system
  • Stealing of files and software
  • Deletion of files
  • Elevation or escalation of privileges
  • Keylogging and potential destruction of the victim file system

Furthermore, Stage 2 malware may also provide the ability for the attacker to migrate to another computer on the same network which provides the ability for even more extensive damage by allowing the attacker to spread out and cause an increase in damage.

Question: Are those the only stages of delivery?

Answer: Not always, but this is the most common.  Sometimes "plugins" or "modules" are available to add to the malware, and they can be delivered or removed on an as needed basis.  The attacker wants to limit the amount of network traffic to a particular domain that is hosting malware as this could lead to detection and blocking, which would stop the potential for successful delivery of any future malware or even stage 2.

Question: Why stage the delivery at all?  Why not just embed all of the malware instead of a portion in the infected document or file?

Answer: There are a few reasons for staging the delivery, one of them being size. Simply put, if the size of the malware is large enough then embedding the whole thing into a PDF would make the file quite large; therefore, more suspicious.  Another reason is to limit the possibility of detection through various scanners and traffic inspectors. The first stage of the malware is quite light in what commands and system calls that it makes which helps to evade detection by signature or even heuristics. It is not uncommon at all to see a PDF reader software open a PDF, then immediately connect to the Internet. Most PDF readers routinely check for updates as soon as they are opened, and attackers know this to be true often enough.  So the stage 1 malware just hides within that behavior, reducing its ability to be detected. Lastly, development of custom malware is expensive and takes time, so losing the entire piece of malware due to detection of any sort can be a huge set back to the attackers. Even if the attackers are using commercial or open source attack tools, rebuilding them to avoid antivirus detection can be time consuming and costly. Losing the stage 1 malware through  detection is easier to address than burning the complete malware package. By staging the delivery it limits the potential loss to the attacker. There many other reasons to break the malware up and retrieve upon infection, but these are some of the most important ones.

Question: This is making more and more sense to me, but just quickly can you go over why it's much harder to detect?

Answer: The smaller and more embedded the malware is, the more difficult to detect, especially inside of a commonly used and trusted file. When the commands for the malware are simplified as well as the needs from a victim computer to execute, again, detection is difficult. When malware is overly complicated, or it has large consumption requirements from the operating system to correctly function, the chances for detection though defense-in-depth techniques is increased. Large, complicated malware is more likely to break and alert the user to its presence, or even get detected by antivirus. It is also most likely to fail Deep Packet Inspection at the IDS/IPS layer due to possible signatures for specific system calls the malware makes. Small, simple malware finds a home inside of the most common files and documents that we not only use and open every day, but also are typically allowable as an attachment in an email. Because the malware is small, it can be easily modified, making signature development almost impossible. Breaking the malware apart also changes which security tools are inspecting the malware. If stage 1 is delivered through an email, than you will have to get through an IDS/IPS, an Email AntiVirus product (if you are dealing with an enterprise), as well as any attachment inspection that occurs on the email gateway. Stage 2 is then delivered after successful infection of victim computer, typically after the victim computer asks a particular web server for the stage 2 malware. If this request is done over SSL/HTTPS, then there is a good chance there will be no inspection of the malware until it reaches the host.  At delivery, the malware has to contend with antivirus on the victim computer, which is trivial for a sophisticated attacker to either bypass or defeat.

Question: If it's so damn hard to detect, how on earth do I stop it?

Answer: Excellent question, this is something we can address in my next blog, "Better Host Based Protection, Logically".

More Stories By Cory Marchand

Cory Marchand is a trusted subject matter expert on topics of Cyber Security Threats, Network and Host based Assessment and Computer Forensics. Mr. Marchand has supported several customers over his 10+ years within the field of Computer Security including State, Federal and Military Government as well as the Private sector. Mr. Marchand holds several industry related certificates including CISSP, EnCE, GSEC, GCIA, GCIH, GREM, GSNA and CEH.

@ThingsExpo Stories
Complete Internet of Things (IoT) embedded device security is not just about the device but involves the entire product’s identity, data and control integrity, and services traversing the cloud. A device can no longer be looked at as an island; it is a part of a system. In fact, given the cross-domain interactions enabled by IoT it could be a part of many systems. Also, depending on where the device is deployed, for example, in the office building versus a factory floor or oil field, security ha...
One of biggest questions about Big Data is “How do we harness all that information for business use quickly and effectively?” Geographic Information Systems (GIS) or spatial technology is about more than making maps, but adding critical context and meaning to data of all types, coming from all different channels – even sensors. In his session at @ThingsExpo, William (Bill) Meehan, director of utility solutions for Esri, will take a closer look at the current state of spatial technology and ar...
For basic one-to-one voice or video calling solutions, WebRTC has proven to be a very powerful technology. Although WebRTC’s core functionality is to provide secure, real-time p2p media streaming, leveraging native platform features and server-side components brings up new communication capabilities for web and native mobile applications, allowing for advanced multi-user use cases such as video broadcasting, conferencing, and media recording.
19th Cloud Expo, taking place November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA, will feature technical sessions from a rock star conference faculty and the leading industry players in the world. Cloud computing is now being embraced by a majority of enterprises of all sizes. Yesterday's debate about public vs. private has transformed into the reality of hybrid cloud: a recent survey shows that 74% of enterprises have a hybrid cloud strategy. Meanwhile, 94% of enterpri...
Cloud computing is being adopted in one form or another by 94% of enterprises today. Tens of billions of new devices are being connected to The Internet of Things. And Big Data is driving this bus. An exponential increase is expected in the amount of information being processed, managed, analyzed, and acted upon by enterprise IT. This amazing is not part of some distant future - it is happening today. One report shows a 650% increase in enterprise data by 2020. Other estimates are even higher....
An IoT product’s log files speak volumes about what’s happening with your products in the field, pinpointing current and potential issues, and enabling you to predict failures and save millions of dollars in inventory. But until recently, no one knew how to listen. In his session at @ThingsExpo, Dan Gettens, Chief Research Officer at OnProcess, will discuss recent research by Massachusetts Institute of Technology and OnProcess Technology, where MIT created a new, breakthrough analytics model f...
Internet of @ThingsExpo has announced today that Chris Matthieu has been named tech chair of Internet of @ThingsExpo 2016 Silicon Valley. The 6thInternet of @ThingsExpo will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA.
There is little doubt that Big Data solutions will have an increasing role in the Enterprise IT mainstream over time. Big Data at Cloud Expo - to be held November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA - has announced its Call for Papers is open. Cloud computing is being adopted in one form or another by 94% of enterprises today. Tens of billions of new devices are being connected to The Internet of Things. And Big Data is driving this bus. An exponential increase is...
DevOps at Cloud Expo, taking place Nov 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA, is co-located with 19th Cloud Expo and will feature technical sessions from a rock star conference faculty and the leading industry players in the world. The widespread success of cloud computing is driving the DevOps revolution in enterprise IT. Now as never before, development teams must communicate and collaborate in a dynamic, 24/7/365 environment. There is no time to wait for long dev...
The Internet of Things will challenge the status quo of how IT and development organizations operate. Or will it? Certainly the fog layer of IoT requires special insights about data ontology, security and transactional integrity. But the developmental challenges are the same: People, Process and Platform and how we integrate our thinking to solve complicated problems. In his session at 19th Cloud Expo, Craig Sproule, CEO of Metavine, will demonstrate how to move beyond today's coding paradigm ...
Fact is, enterprises have significant legacy voice infrastructure that’s costly to replace with pure IP solutions. How can we bring this analog infrastructure into our shiny new cloud applications? There are proven methods to bind both legacy voice applications and traditional PSTN audio into cloud-based applications and services at a carrier scale. Some of the most successful implementations leverage WebRTC, WebSockets, SIP and other open source technologies. In his session at @ThingsExpo, Da...
Cognitive Computing is becoming the foundation for a new generation of solutions that have the potential to transform business. Unlike traditional approaches to building solutions, a cognitive computing approach allows the data to help determine the way applications are designed. This contrasts with conventional software development that begins with defining logic based on the current way a business operates. In her session at 18th Cloud Expo, Judith S. Hurwitz, President and CEO of Hurwitz & ...
SYS-CON Events announced today that Roundee / LinearHub will exhibit at the WebRTC Summit at @ThingsExpo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. LinearHub provides Roundee Service, a smart platform for enterprise video conferencing with enhanced features such as automatic recording and transcription service. Slack users can integrate Roundee to their team via Slack’s App Directory, and '/roundee' command lets your video conference ...
Digital transformation is too big and important for our future success to not understand the rules that apply to it. The first three rules for winning in this age of hyper-digital transformation are: Advantages in speed, analytics and operational tempos must be captured by implementing an optimized information logistics system (OILS) Real-time operational tempos (IT, people and business processes) must be achieved Businesses that can "analyze data and act and with speed" will dominate those t...
IoT is fundamentally transforming the auto industry, turning the vehicle into a hub for connected services, including safety, infotainment and usage-based insurance. Auto manufacturers – and businesses across all verticals – have built an entire ecosystem around the Connected Car, creating new customer touch points and revenue streams. In his session at @ThingsExpo, Macario Namie, Head of IoT Strategy at Cisco Jasper, will share real-world examples of how IoT transforms the car from a static p...
Internet of @ThingsExpo, taking place November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA, is co-located with the 19th International Cloud Expo and will feature technical sessions from a rock star conference faculty and the leading industry players in the world and ThingsExpo Silicon Valley Call for Papers is now open.
The Transparent Cloud-computing Consortium (abbreviation: T-Cloud Consortium) will conduct research activities into changes in the computing model as a result of collaboration between "device" and "cloud" and the creation of new value and markets through organic data processing High speed and high quality networks, and dramatic improvements in computer processing capabilities, have greatly changed the nature of applications and made the storing and processing of data on the network commonplace.
Almost two-thirds of companies either have or soon will have IoT as the backbone of their business in 2016. However, IoT is far more complex than most firms expected. How can you not get trapped in the pitfalls? In his session at @ThingsExpo, Tony Shan, a renowned visionary and thought leader, will introduce a holistic method of IoTification, which is the process of IoTifying the existing technology and business models to adopt and leverage IoT. He will drill down to the components in this fra...
SYS-CON Events announced today that ReadyTalk, a leading provider of online conferencing and webinar services, has been named Vendor Presentation Sponsor at the 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. ReadyTalk delivers audio and web conferencing services that inspire collaboration and enable the Future of Work for today’s increasingly digital and mobile workforce. By combining intuitive, innovative tec...
I'm a lonely sensor. I spend all day telling the world how I'm feeling, but none of the other sensors seem to care. I want to be connected. I want to build relationships with other sensors to be more useful for my human. I want my human to understand that when my friends next door are too hot for a while, I'll soon be flaming. And when all my friends go outside without me, I may be left behind. Don't just log my data; use the relationship graph. In his session at @ThingsExpo, Ryan Boyd, Engi...