1. Hunting for Unfriendly Easter Eggs
Capturing evidence of APT attacks
Michael Robinson & Craig Astrich

2. Michael Robinson Craig Astrich
Introductions
Michael Robinson Craig Astrich

3. Defining Advanced Persistent Threat (APT)
Historical Note
Defining Advanced Persistent Threat (APT)
Term originated within the U.S. Air Force in 2006.
Originally used so Air Force personnel could discuss a series of attacks attributed to a specific set of actors located in Asia-Pacific region with uncleared partners.
The term appeared more publicly in in conferences.
The term has hit mainstream media in 2010 with the announcement of Operation Aurora.
Attacks from foreign adversaries occurred before 2006.

4. Defensive/protective measures
APT Model
Cloppert’s Kill Chain
Model created in Desire to break the chain as far to the left as possible.
Clean-up costs
Defensive/protective measures

5. Lots of activity grouped together
APT Model
Cloppert’s Kill Chain
Recognized, but the model has limitations. Not effective in defining all of the characteristics of the life cycle.
Lots of activity grouped together

6. Shift in Term’s Meaning
New de facto Model
Shift in Term’s Meaning
Specific attacker/actor
Attack with specific characteristics
ATTRIBUTION

7. Tremendous Confusion Over the Term’s Meaning
New de facto Model
Tremendous Confusion Over the Term’s Meaning
Is it a person or an attack type? Are the attackers nation states, terrorists, organizations or individuals? Does it necessarily involve zero day exploitation? Is customized malware always involved? Do these attacks frequently use social networking/phishing attacks? Are targets information resources or financial repositories? Is it marketing hype?

8. Combined, do the terms clearly articulate the challenge?
APT Definition – What do these terms mean?
As a Proper Noun?
As malware?
Advanced Skills that run the full gamut. Capable of using basic tools and writing custom code. Persistent Long-term interest and continued targeting. Threat A person who mans the console behind the attack, rather the pre-configured malware (set it and forget it).
It isn’t detected by AV.
It survives reboots.
It that could steal data that would be harmful to the organization.
Combined, do the terms clearly articulate the challenge?

9. Move from the APT Kill Chain to the APT Life Cycle
Redefining the Model
Move from the APT Kill Chain to the APT Life Cycle
Expand APT attacks into a full life cycle to obtain a better understanding. The lifecycle recognizes the iterative process where an adversary obtains a deeper foothold into the network through lateral movement.

10. Move from the APT Kill Chain to the APT Life Cycle
Redefining the Model
Move from the APT Kill Chain to the APT Life Cycle
Interpreting data associated with each step to be based on use cases rather opinion.

11. Typical Attack SMTP Relay; Botnet C2 Server Mail Server
Domain Controller

12. Example of an Attack SMTP Relay; Botnet C2 Server Mail Server
Indicators of Compromise (IOCs)
Inbound with attachment
Attachment cached in OLK folder
Attachment executed – Prefetch
Outbound connection established
File downloaded
File cached - Change Journal entry
File executed - Prefetch file created
New DLL created
Autostart/autorun locations modified Restore Point modified
Service restarted with injected DLL
Indicators of Compromise (IOCs)
Outbound connection
New file downloaded
Lateral traffic
Query of Domain Controller
Existing accounts modified
Mail Server
Domain Controller

13. Example of an Attack
What a mess.

14. Redefining the Model
Review of each step…

15. …produces a comprehensive list of indicators.
Redefining the Model
…produces a comprehensive list of indicators.

16. Redefining the Model Results of Analysis
300+ Indicators of Compromise (IOCs) were identified.
IOCs were identified from multiple sources, i.e., disk, files, memory, and network traffic.
The appearance of an individual IOC is likely to be insignificant.
When multiple IOCs appear within close proximity of each other, i.e., clustering of events, the severity of an incident increases and the likelihood of a false positive decreases.
Many IOCs are not monitored by typical security controls.

17. Step 1-1: Initial Reconnaissance
APT Life Cycle
Step 1-1: Initial Reconnaissance
Profile information is acquired about the organization and it’s employees.
Sources of information about primary/secondary targets may come from the following sources:
- Press releases
- Corporate websites
- Job postings
- Tech forums
- DNS records and registration
- Social network sites, e.g., Facebook, LinkedIn, Spokeo
- Pastebin

18. Step 1-2: External Weaponization
APT Life Cycle
Step 1-2: External Weaponization
Two sets of tools may be leverages as weapons.
Custom malware may be developed based on targeted intelligence obtained during the initial reconnaissance phase that leverages the use of carefully choreographed social engineering.
Generic tools to be used during a “shotgun” approach could be used to “blast” all of the users of a network, as in a large spam/phishing campaign.

19. Step 1-3: External Delivery
APT Life Cycle
Step 1-3: External Delivery
Malicious payload is delivered to a victim via online or physical means.
The attack vectors may include:
- Spam/Phishing
- Spoofed /Spear Phishing/Whaling
- Social networking sites
- External media (USB storage media, CD/DVDs)
- Network probe via Wi-Fi
- An external resource, such as DNS cache, is modified.

20. Step 1-3: External Delivery
APT Life Cycle
Step 1-3: External Delivery
Indicators of Compromise may include:
- Identical spam in multiple users’ mailboxes
- where origin SMTP IP address does not match domain name (reverse lookup)
- ’s SMTP address originates from an open relay (which accounts for 20% of spam on the Internet)
- Unauthorized use of USB ports
- Unauthorized network traffic
- Unauthorized CD/DVDs in the workplace
- Connections to websites with malicious content or sites with known drive-by attacks

21. Step 1-4: Initial Exploitation
APT Life Cycle
Step 1-4: Initial Exploitation
The malicious content has been sent to the target(s) and the payload is executed locally.
Examples of an initial exploitation activity include:
- A link that has been clicked by the user.
- An attachment that is opened.
- An object on a web page that is automatically executed by a browser or browser helper object (BHO).
- A CD/DVD is inserted into a computer and a file is open or executed.
Indicators of Compromise may include:
- Unresolved IP address and SMTP server
- Redirects to hostile websites
- Malicious JavaScript in a user’s cached Internet files
- Executable files in a user’s cached Internet files, which may include .exe files, Flash files, etc.
- PDFs with malicious content with OLK cache
- Changes to the MUI cache
- Modifications to the local HOSTS file
- LNK file appears

22. Tangent: LNK Files These timestamps are of the target file.
(Remember, these are stored within the LNK file. EnCase didn’t query the target file.)
Location of the target file.
Volume Serial Number
This should match the volume serial number of this particular drive, because the target path is C:\...
MAC address of NIC on the computer where the shortcut was created.

23. Step 1-5: Initial Installation
APT Life Cycle
Step 1-5: Initial Installation
Malicious software is installed on the system that has been targeted and exploited.
This could result in the download and installation of a second-stage piece of malware.
The running of the malicious software may result in a new application running or a new file being injected into a running process.
Indicators of Compromise may include:
- Objects in the Internet cache
- Files in OLK cache folder
- Attachments with executable code within s
- Files with MZ header in the temp folder of the user’s profile or within C:\Windows\Temp.
- New Prefetch files which include references to new drivers or recently downloaded files
- Modifications to existing software drivers
- Artifacts for persistence, e.g., addition to the autorun locations within the Windows Registry
- Changes to $USN_Journal, especially code 0x0100
- Outbound network traffic in the form of a beacon or DNS lookup to confirm network connectivity. (Lookups may use hostile sites, but may also use well-known sites with high up-time).

24. Tangent: $USN Journal Codes
0x01 Data in one or more named data streams for the file was overwritten.
0x02 The file or directory was added to.
0x04 The file or directory was truncated.
0x10 Data in one or more named data streams for the file was overwritten.
0x20 One or more named data streams for the file were added to.
0x40 One or more named data streams for the file was truncated.
0x100 The file or directory was created for the first time.
0x200 The file or directory was deleted.
0x400 The user made a change to the file's or directory's extended attributes. These NTFS attributes are not accessible to Windows-based applications.
0x800 A change was made in the access rights to the file or directory.
0x1000 The file or directory was renamed, and the file name in this structure is the previous name.
0x2000 The file or directory was renamed, and the file name in this structure is the new name.
0x4000 A user changed the FILE_ATTRIBUTE_NOT_CONTENT_INDEXED attribute. That is, the user changed the file or directory from one that can be content indexed to one that cannot, or vice versa.
0x8000 A user has either changed one or more file or directory attributes or one or more time stamps.
0x A named stream has been added to or removed from the file, or a named stream has been renamed.
0x The file or directory was closed.
Reference:
0x100 indicates a file was created.
0x200 indicates a file was deleted.
0x2000 indicates a file was renamed.
0x indicates a file was closed.

25. Tangent: $USN Journal Example
The same file identifier was used throughout the process.
Action
Name
File ID
Code
Time
A new file is created on the drive with the name badcode.exe.
badcode.exe
89245
0x100
05/28/12 09:28:25
0x100
+ 0x02
0x102
Content is added to badcode.exe.
badcode.exe
89245
05/28/12 09:28:27
At this point, the file is closed and there is no activity on the disk.
0x102
+ 0x 0x
badcode.exe is closed.
badcode.exe
89245
05/28/12 09:28:27
Renames should always appear in pairs.
The file is renamed from badcode.exe to svchost.exe
badcode.exe
89245
0x1000
05/28/12 09:28:29
svchost.exe
89245
0x2000
05/28/12 09:28:29
0x2000
+ 0x 0x
svchost.exe
89245
05/28/12 09:28:29

26. Step 1-6: Command & Control Activity
APT Life Cycle
Step 1-6: Command & Control Activity
The infected computer establishes a connection with a remote computer. While this may involve creation of listener that responds to an inbound connection, it will likely be an executable or injected process that creates an outbound connection to a remote host. The remote host may be a command and control server, it could be a proxy server, or an infected computer that is part of a botnet.
Indicators of Compromise may include:
- New running processes
- Restarted running processes which contain injected code
- New Prefetch files which include references to new drivers or recently downloaded files
- Disabling of normal services, e.g., anti-virus engines or the local firewall
- Outbound network traffic
- Network connections stored on the infected computer to non-legitimate sources.

27. Tangent: Prefetch Files
08/19/09 01:22:19PM

28. Prefetch File Analysis: WinPrefetchView

29. Step 2-1: Internal Reconnaissance
APT Life Cycle
Step 2-1: Internal Reconnaissance
Information is gained about the infected computer and LAN.
Sources of information used during reconnaissance may include:
- OS footprint
- User name and profile information
- IP addresses/DHCP information
- Domain name
- Names of network, e.g., list of domain controllers, internal DNS servers, and network services
- Network connections
Indicators of Compromise may include:
- Connectivity to an Internet-based resource used to deliver commands to the infected computer
- Lateral network traffic and PINGs
- Connections to network shares
- Abnormal running services/processes
- Creation of Prefetch files for network diagnostic tools, such as netstat
- Additions to the UserAssist Registry keys
- Installation of administrator tools on the infected computer to perform reconnaissance activities

30. Step 2-2: Internal Weaponization
APT Life Cycle
Step 2-2: Internal Weaponization
The tools used to internally compromised are not necessarily the same as those used to gain initial access to the system.
These tools may be administrator tools, such as PSEXEC. Some may be customized.
Indicators of Compromise may include:
- Connectivity to an Internet-based resource used to deliver commands to the infected computer
- Installation of new executable files to the user’s profile or C:\Windows\System32 directory.
- Changes to $USN_Journal, especially code 0x0100
- Creation of Prefetch files to indicate existing administration tools were run.

31. Step 2-3: Internal Delivery
APT Life Cycle
Step 2-3: Internal Delivery
Tools used for the advancement throughout the network are copied to the infected computer.
Indicators of compromise may include:
- Connectivity to an Internet-based resource used to deliver commands to the infected computer
- New files on the file system
- Modifications to timestamps; inconsistencies between $SIA and $FN portions of the $MFT
- Changes to the $USN_Journal, especially code 0x0100
- Changes to the list of network connections maintained within memory of the infected computers
- Internal, lateral network traffic

32. All eight timestamps are in $MFT.
Tangent: Timestamps
All eight timestamps are in $MFT.
$STANDARD_INFORMATION
Type: 0x10
Min Size: 0x30
Max Size: 0x48
Read offset to attribute content and add:
Created (0x00)
Last Modified (0x08)
MFT Entry Modified (0x10)
Last Accessed (0x18)
$FILE_NAME
Type: 0x30
Min Size: 0x44
Max Size: 0x242
Read offset to attribute content and add:
Created (0x08)
Last Modified (0x10)
MFT Entry Modified (0x18)
Last Accessed (0x20)

33. Standard Information Attribute
Tangent: Timestamps
Standard Information Attribute
Created: 12/29/2011 9:00:00AM
Last Modified: 12/29/2011 9:00:00AM
Last Access: 12/29/2011 9:00:00AM
MFT Entry: 01/13/ :15:30AM
Standard Information Attribute
File Name Attribute
Created: 01/13/ :13:18AM
Last Modified: 01/13/ :13:18AM
Last Access: 01/13/ :13:18AM
MFT Entry: 01/13/ :13:18AM
File
Name Attribute

34. Step 2-4: Internal Exploitation
APT Life Cycle
Step 2-4: Internal Exploitation
During internal exploitation an attacker positions himself to move laterally by compromising the integrity of another system within the network. This may involve obtaining escalated privileges, exploiting the operating system, user application, or implanting code that will execute.
Indicators of compromise may include:
- Connectivity to an Internet-based resource used to deliver commands from the infected computer
- New files on the file system
- Modifications to timestamps; inconsistencies between $SIA and $FN portions of the $MFT
- Changes to the $USN_Journal, especially code 0x0100
- Modifications to the autorun locations, which would allow an executable to launch or inject malicious code with a known process, e.g., explorer.exe
- Internal, lateral network traffic

35. Lateral Connections within the LAN
C:\Users\robinson>netstat -ano
Active Connections
Proto Local Address Foreign Address State PID
TCP : :0 LISTENING 964
TCP : :0 LISTENING 4
TCP : :0 LISTENING 3624
TCP : :0 LISTENING 1492
TCP : :0 LISTENING 4
TCP : :5061 ESTABLISHED 5708
TCP : :8080 ESTABLISHED 7340
TCP : :80 ESTABLISHED 1320
TCP : :2310 CLOSE_WAIT 4784
TCP : :0 LISTENING 3136
TCP : :52444 TIME_WAIT 0
This IP address is for a neighboring PC.
Why?

36. Step 2-5: Internal Installation
APT Life Cycle
Step 2-5: Internal Installation
During the internal installation phase an attacker compromises the integrity of another system within the network. This may involve exploiting the operating system, exploiting a user application, or implanting malicious code that will execute. The insertion of this code would circumvent intrusion detection systems. The use of known, legitimate administration tools would not be captured by anti-virus software.
Indicators of compromise may include:
- Connectivity to an Internet-based resource from the initially infected computer.
- Connectivity to an Internet-based resource used to deliver commands to the newly infected computer
- New running processes
- Restart of existing processes to include injected code
- Creation of Prefetch files to indicate existing administration or malicious tools were run.
- Internal, lateral network traffic

37. APT Life Cycle Step 2-6: Persistence
An attacker establishes persistence on a network when he maintains a presence in the network as various machines go offline or as incident response procedures are implemented. This will frequently involve establishing connectivity with multiple hosts on the compromised network.
Indicators of compromise may include:
- Connectivity to an Internet-based resource from the initially infected computer.
- Connectivity to an Internet-based resource from the multiple computers. This may be a beacon to test connectivity, e.g., DNS lookups, etc.
- Outbound network traffic from computers that don’t typically communicate to the Internet, e.g., print servers, domain controllers
- New running processes
- Restart of existing processes to include injected code
- Addition of Prefetch files
- Internal, lateral network traffic
- New user accounts on local hosts or within a domain controller
- Change of permissions/rights/roles of existing network accounts.

38. APT Life Cycle Iterative Process
Once inside the network, the attacker engages in an iterative process to retain a foothold within the compromised network.
This can result in:
New malware being launched within the network to upgrade existing malware that may be detected by anti-virus software
Disabling network security safeguards to avoid detection
Erasing artifacts, such as log files, etc.
Lateral traffic between computers.

39. APT Life Cycle Iterative Process Indicators of Compromise may include:
- Connectivity to an Internet-based resource from the multiple computers.
- Outbound network traffic from computers that don’t typically communicate to the Internet, e.g., print servers, domain controllers
- New running processes
- Restart of existing processes to include injected code
- Creation of Prefetch files to indicate existing administration or malicious tools were run.
- Internal, lateral network traffic
- New user accounts on local hosts or within a domain controller
- Change of permissions/rights/roles of existing network accounts.
- Reinfection of previously cleaned computers
- Exfiltration data files on computers. This may include the presence of empty files that are re-used.
Iterative Process

40. 2-7: Mission Fulfillment
APT Life Cycle
2-7: Mission Fulfillment
An attacker successfully fulfills his mission, which may include:
- the exfiltration of data from the network
- launching a denial of service attack
- incorporate infected computers into a botnet
Indicators of compromise may include:
- Connectivity to an Internet-based resource from the multiple computers.
- Outbound network traffic from computers that don’t typically communicate to the Internet, e.g., print servers, domain controllers
- New running processes
- Restart of existing processes to include injected code
- Addition of Prefetch files
- Internal, lateral network traffic
- New user accounts on local hosts or within a domain controller
- Change of permissions/rights/roles of existing network accounts.

41. Hunting for Unfriendly Easter Eggs
5/22/2012
Hunting for Unfriendly Easter Eggs
Capturing evidence of APT attacks
Michael Robinson & Craig Astrich
Craig Astrich and Michael Robinson