Click here to close now.

Welcome!

Security Authors: Elizabeth White, Liz McMillan, Pat Romanski, Irit Gillath, Tom Scearce

Related Topics: Security

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
The cloud is now a fact of life but generating recurring revenues that are driven by solutions and services on a consumption model have been hard to implement, until now. In their session at 16th Cloud Expo, Ermanno Bonifazi, CEO & Founder of Solgenia, and Ian Khan, Global Strategic Positioning & Brand Manager at Solgenia, will discuss how a top European telco has leveraged the innovative recurring revenue generating capability of the consumption cloud to enable a unique cloud monetization model to drive results.
As organizations shift toward IT-as-a-service models, the need for managing and protecting data residing across physical, virtual, and now cloud environments grows with it. CommVault can ensure protection &E-Discovery of your data – whether in a private cloud, a Service Provider delivered public cloud, or a hybrid cloud environment – across the heterogeneous enterprise. In his session at 16th Cloud Expo, Randy De Meno, Chief Technologist - Windows Products and Microsoft Partnerships, will discuss how to cut costs, scale easily, and unleash insight with CommVault Simpana software, the only si...
Docker is an excellent platform for organizations interested in running microservices. It offers portability and consistency between development and production environments, quick provisioning times, and a simple way to isolate services. In his session at DevOps Summit at 16th Cloud Expo, Shannon Williams, co-founder of Rancher Labs, will walk through these and other benefits of using Docker to run microservices, and provide an overview of RancherOS, a minimalist distribution of Linux designed expressly to run Docker. He will also discuss Rancher, an orchestration and service discovery platf...
Analytics is the foundation of smart data and now, with the ability to run Hadoop directly on smart storage systems like Cloudian HyperStore, enterprises will gain huge business advantages in terms of scalability, efficiency and cost savings as they move closer to realizing the potential of the Internet of Things. In his session at 16th Cloud Expo, Paul Turner, technology evangelist and CMO at Cloudian, Inc., will discuss the revolutionary notion that the storage world is transitioning from mere Big Data to smart data. He will argue that today’s hybrid cloud storage solutions, with commodity...
Cloud data governance was previously an avoided function when cloud deployments were relatively small. With the rapid adoption in public cloud – both rogue and sanctioned, it’s not uncommon to find regulated data dumped into public cloud and unprotected. This is why enterprises and cloud providers alike need to embrace a cloud data governance function and map policies, processes and technology controls accordingly. In her session at 15th Cloud Expo, Evelyn de Souza, Data Privacy and Compliance Strategy Leader at Cisco Systems, will focus on how to set up a cloud data governance program and s...
Roberto Medrano, Executive Vice President at SOA Software, had reached 30,000 page views on his home page - http://RobertoMedrano.SYS-CON.com/ - on the SYS-CON family of online magazines, which includes Cloud Computing Journal, Internet of Things Journal, Big Data Journal, and SOA World Magazine. He is a recognized executive in the information technology fields of SOA, internet security, governance, and compliance. He has extensive experience with both start-ups and large companies, having been involved at the beginning of four IT industries: EDA, Open Systems, Computer Security and now SOA.
Every innovation or invention was originally a daydream. You like to imagine a “what-if” scenario. And with all the attention being paid to the so-called Internet of Things (IoT) you don’t have to stretch the imagination too much to see how this may impact commercial and homeowners insurance. We’re beyond the point of accepting this as a leap of faith. The groundwork is laid. Now it’s just a matter of time. We can thank the inventors of smart thermostats for developing a practical business application that everyone can relate to. Gone are the salad days of smart home apps, the early chalkb...
The industrial software market has treated data with the mentality of “collect everything now, worry about how to use it later.” We now find ourselves buried in data, with the pervasive connectivity of the (Industrial) Internet of Things only piling on more numbers. There’s too much data and not enough information. In his session at @ThingsExpo, Bob Gates, Global Marketing Director, GE’s Intelligent Platforms business, to discuss how realizing the power of IoT, software developers are now focused on understanding how industrial data can create intelligence for industrial operations. Imagine ...
We certainly live in interesting technological times. And no more interesting than the current competing IoT standards for connectivity. Various standards bodies, approaches, and ecosystems are vying for mindshare and positioning for a competitive edge. It is clear that when the dust settles, we will have new protocols, evolved protocols, that will change the way we interact with devices and infrastructure. We will also have evolved web protocols, like HTTP/2, that will be changing the very core of our infrastructures. At the same time, we have old approaches made new again like micro-services...
Operational Hadoop and the Lambda Architecture for Streaming Data Apache Hadoop is emerging as a distributed platform for handling large and fast incoming streams of data. Predictive maintenance, supply chain optimization, and Internet-of-Things analysis are examples where Hadoop provides the scalable storage, processing, and analytics platform to gain meaningful insights from granular data that is typically only valuable from a large-scale, aggregate view. One architecture useful for capturing and analyzing streaming data is the Lambda Architecture, representing a model of how to analyze rea...
SYS-CON Events announced today that Vitria Technology, Inc. will exhibit at SYS-CON’s @ThingsExpo, which will take place on June 9-11, 2015, at the Javits Center in New York City, NY. Vitria will showcase the company’s new IoT Analytics Platform through live demonstrations at booth #330. Vitria’s IoT Analytics Platform, fully integrated and powered by an operational intelligence engine, enables customers to rapidly build and operationalize advanced analytics to deliver timely business outcomes for use cases across the industrial, enterprise, and consumer segments.
Today’s enterprise is being driven by disruptive competitive and human capital requirements to provide enterprise application access through not only desktops, but also mobile devices. To retrofit existing programs across all these devices using traditional programming methods is very costly and time consuming – often prohibitively so. In his session at @ThingsExpo, Jesse Shiah, CEO, President, and Co-Founder of AgilePoint Inc., discussed how you can create applications that run on all mobile devices as well as laptops and desktops using a visual drag-and-drop application – and eForms-buildi...
Containers and microservices have become topics of intense interest throughout the cloud developer and enterprise IT communities. Accordingly, attendees at the upcoming 16th Cloud Expo at the Javits Center in New York June 9-11 will find fresh new content in a new track called PaaS | Containers & Microservices Containers are not being considered for the first time by the cloud community, but a current era of re-consideration has pushed them to the top of the cloud agenda. With the launch of Docker's initial release in March of 2013, interest was revved up several notches. Then late last...
SYS-CON Events announced today that Dyn, the worldwide leader in Internet Performance, will exhibit at SYS-CON's 16th International Cloud Expo®, which will take place on June 9-11, 2015, at the Javits Center in New York City, NY. Dyn is a cloud-based Internet Performance company. Dyn helps companies monitor, control, and optimize online infrastructure for an exceptional end-user experience. Through a world-class network and unrivaled, objective intelligence into Internet conditions, Dyn ensures traffic gets delivered faster, safer, and more reliably than ever.
CommVault has announced that top industry technology visionaries have joined its leadership team. The addition of leaders from companies such as Oracle, SAP, Microsoft, Cisco, PwC and EMC signals the continuation of CommVault Next, the company's business transformation for sales, go-to-market strategies, pricing and packaging and technology innovation. The company also announced that it had realigned its structure to create business units to more directly match how customers evaluate, deploy, operate, and purchase technology.
In their session at @ThingsExpo, Shyam Varan Nath, Principal Architect at GE, and Ibrahim Gokcen, who leads GE's advanced IoT analytics, focused on the Internet of Things / Industrial Internet and how to make it operational for business end-users. Learn about the challenges posed by machine and sensor data and how to marry it with enterprise data. They also discussed the tips and tricks to provide the Industrial Internet as an end-user consumable service using Big Data Analytics and Industrial Cloud.
The explosion of connected devices / sensors is creating an ever-expanding set of new and valuable data. In parallel the emerging capability of Big Data technologies to store, access, analyze, and react to this data is producing changes in business models under the umbrella of the Internet of Things (IoT). In particular within the Insurance industry, IoT appears positioned to enable deep changes by altering relationships between insurers, distributors, and the insured. In his session at @ThingsExpo, Michael Sick, a Senior Manager and Big Data Architect within Ernst and Young's Financial Servi...
Performance is the intersection of power, agility, control, and choice. If you value performance, and more specifically consistent performance, you need to look beyond simple virtualized compute. Many factors need to be considered to create a truly performant environment. In his General Session at 15th Cloud Expo, Harold Hannon, Sr. Software Architect at SoftLayer, discussed how to take advantage of a multitude of compute options and platform features to make cloud the cornerstone of your online presence.
Even as cloud and managed services grow increasingly central to business strategy and performance, challenges remain. The biggest sticking point for companies seeking to capitalize on the cloud is data security. Keeping data safe is an issue in any computing environment, and it has been a focus since the earliest days of the cloud revolution. Understandably so: a lot can go wrong when you allow valuable information to live outside the firewall. Recent revelations about government snooping, along with a steady stream of well-publicized data breaches, only add to the uncertainty
The explosion of connected devices / sensors is creating an ever-expanding set of new and valuable data. In parallel the emerging capability of Big Data technologies to store, access, analyze, and react to this data is producing changes in business models under the umbrella of the Internet of Things (IoT). In particular within the Insurance industry, IoT appears positioned to enable deep changes by altering relationships between insurers, distributors, and the insured. In his session at @ThingsExpo, Michael Sick, a Senior Manager and Big Data Architect within Ernst and Young's Financial Servi...