Memory Forensics During Incident Response

Jack CrookIncident Handler

Works for GE

Founded RaDFIRe

Handlerdiaries.com

IR in a nutshell

Consider the following scenario

It’s been a long night and you finally get to bed only to be woken up 30 minutes later to the sound of your phone alerting you that there’s an alert that fired and needs to be triaged immediately.  Crawling out of bed you’re thinking this has to be a false positive because you’ve gone through this same routine each of the past 5 nights you were on call.  Not bothering to turn the lights on for something that’s sure to be random noise,  you peer into the ids console and see an alert that you have never seen before.  You automatically think to yourself, being the tired analyst that you are, “who was the a$$hole that added this new rule”, and you’re sure it was added intentionally just to keep you awake, but you know you can’t get back to bed until the alert is validated.  So you begin sifting through the data and it quickly becomes apparent that this isn’t a false positive, but rather it’s the real deal and alerted to the fact that there’s an intruder in your network attempting to move laterally.  You double check your initial analysis and you come to the realization that you’re not going to feel the comfort of your bed for a long long time to come.  As the adrenaline begins to rush, your mind starts racing, thinking about everything that needs to happen and you know you need to act immediately.

Questions that need answered

Is there a compromise?

How was access

obtained?

When do I contain?

How many points of

access are there?

What is the scope of the

incident?

Was there any data

exfil?

Useful Data Types Knowing which data will give you the most information when

analyzing intrusions and being able to quickly collect that data is critical.

• Network (PCAP / Netflow)• OS logs• AV, HIPS/HIDS Logs• MFT• Memory• Pagefile• Prefetch• Registry Hives

Host based analysis

Questions that need answered

Is host compromised?

What was

placed on the host?

Was lateral

movement

performed?

Was there

any data exfil?

Are additiona

l hosts compromised?

Memory is one if the richest pieces of data to collect when analyzing

host data

WHY COLLECT MEMORY?

Acquisition times

Complete system state

Recover artifacts of compromise

Identify command execution

Tools for acquiring memory There are several tools that you can use to acquire memory

during forensic investigations.• DumpIt (Moonsols)• Fastdump Pro (HBGary)• Memoryze (Mandiant)• FTK Imager (FTK)

Analysis Tools There are several freely available tools that you can use to

aid in your forensic investigations.• Volatility• Rekall• Redline• Responder• Strings• Grep• dd

Questions we can often answer?Is the host compromised? How was the host compromised?

Were malicious files dropped? Who talked to the host?

Who did the host talk to? Were any user accts compromised?

Was any lateral movement identified? How was lateral movement performed?

Was any data taken from the host? Do additional hosts need investigation?

What can we glean?

Memory Terms Some key terms that will be explained in the following

slides :• Virtual Memory• Stack Memory• Heap Memory• Paging• Memory management• VAD’s• Shared Memory

Memory TermsVirtual Memory: A mechanism used so that each process can have it’s own

memory space without bleeding into other process space.

Stack Memory: This is basically the runtime state of process. This area of

memory includes data such as local variables and functions. All processes.

Heap Memory: This area of memory is used for the dynamic allocation. File

contents and user input are some of the data types in heap memory. All processes.

Memory TermsPaging: Also know as swapping. Used when physical memory for

that process is exhausted. Pages from memory are written to disk to free physical memory space. When a swapped page is needed it is retrieved from disk and rewritten to memory.

Memory Management: The operating system’s process of allocating and tracking

allocated memory.

Memory TermsVAD: Also known as Virtual Address Descriptors. It’s the method

used to record the usage of virtual addresses. It’s possible to rebuild an entire process (minus paged data) by walking this tree like structure and extracting each page.

Shared Memory: Used for processes to share different pieces of memory.

Think of dll’s.

Demo 2012 GrrCON forensic challenge https://docs.google.com/file/d/

0B_xsNYzneAhEQXNZSzh6YTVZQ3M/edit