BSides Seattle 2019 talk about operating against macOS devices with a new open source tool called Apfell

1. READY PLAYER 2
MULTIPLAYER RED TEAMING
AGAINST MACOS
BSIDES SEATTLE 2019

2. CODY THOMAS
• Senior Operator at SpecterOps
• Previously:
• Adversary Emulation Engineer at MITRE
• Mac/Linux ATT&CK
• APT3 Emulation Plan
• Twitter: @its_a_feature_
• GitHub: github.com/its-a-feature/
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3. MACOS OPERATIONS
What’s the current landscape?
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4. CURRENT MACOS OPERATIONS
Malware seen in the wild:
• WindTail
• Signed macOS application
• FairyTale:
• Signed macOS application
• Calisto
• Unsigned macOS application
• AppleJeus
• Signed macOS application
• EvilEgg and LamePyre
• Utilize EggShell and Empire
Red Teaming FOSS Frameworks:
• Empire
• Python-based agent
• Single User Terminal Application
• RESTful Interface
• EggShell
• Python-based agent
• Single User Terminal Application
• Evil OSX
• Python-based agent
• Some GUI components
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https://objective-see.com/downloads/MacMalware_2018.pdf
https://github.com/EmpireProject/Empire
https://github.com/neoneggplant/EggShell
https://github.com/Marten4n6/EvilOSX

5. OPERATIONAL PROBLEMS
● Want to emulate adversaries, but:
○ Current FOSS capabilities don’t match up
○ More easily caught as “Red Team”
○ Signing macOS applications is not easy
● Want to operate in a team, but:
○ Need proper collaboration and sharing
○ Screen sharing isn’t scalable
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6. BRIDGING THE GAP
How can we get operations closer to the real
thing?
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7. JAVASCRIPT FOR AUTOMATION (JXA)
● Scriptable execution:
○ Most of the lower-level Objective C APIs exposed in a JS way
○ Kind of like if PowerShell stopped at version 1 or 2
● According to Apple:
“In OS X 10.10, JavaScript became a peer to AppleScript in OS X.”
● Still isn’t a signed macOS Application though
○ Hard to emulate as a consultant across multiple customers
● Very limited threading capabilities
7https://developer.apple.com/library/archive/documentation/LanguagesUtilities/Conceptual/MacAutomationScriptingGuide/index.html

8. ● Does osascript normally run?
○ AppleScript has been around since 1993
○ Mainly used by Admins and power users
● How does JXA perform actions?
○ Apple Events for IPC (causes popups in 10.14)
○ Objective C API calls
● Signing?
○ Not a problem – Live off the land
○ osascript is an Apple signed binary
○ Can execute entirely in memory
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DEFENSIVE CONSIDERATIONS

9. NOW IT’S TIME TO OP
You’ve been tasked to operate
against macOS, now what?
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10. 10
INTRODUCING
It’s not a bug, it’s a feature

11. WHAT IS APFELL?
● Collaborative, post-exploitation framework with a web front-end
● Apfell server runs on MacOS/Linux (needs python3.6+)
● Apfell agents can be any operating system
○ JXA payload for macOS
○ @xorrior already released a Chrome extension payload
○ Payloads can be scripted or dynamically compiled
● Any number of c2 profiles running at a time
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12. DEMO TIME!
Let’s operate
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Demo videos:
● https://youtu.be/9yjNzYtOyHE
● https://youtu.be/FJf9oQkBG0g
● https://youtu.be/_V7PrbDHfY8
● https://youtu.be/Hgn-RUa9feo
● https://youtu.be/4mABpw20KMQ
● https://youtu.be/KypCqWSQGwE

13. A FRAMEWORK SHOULD BE:
1. Informative
• Track data, environment, operation, OPSEC concerns
• Easy to understand user interface
• Purple in nature - helping both Red and Blue teams
2. Collaborative
• Every operator has their own customized front-end
• Can share detailed information easily and quickly
3. Extensible
• Easily add/share commands, C2 profiles, payloads
• Support multiple operating systems
• You shouldn’t have to re-roll a UI for every new payload
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14. INFORMATIVE: FOR RED TEAMERS
● Operators
● Commands
○ OPSEC (Artifacts, Transforms)
● Payload Types
○ Creation, loading modules, execution help
● Operational Data Model
○ Let’s use all the data we collect/generate in operations
● Task-Response grouping
○ not just data-dump console
● Searching tasks and responses across an operation
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15. INFORMATIVE: FOR BLUE TEAMERS
● Commands mapped to MITRE ATT&CK
○ Regex matching for more granularity
○ Exports to ATT&CK Navigator
○ Auto populates based on the command
● Host/Network artifact tracking per task
○ Helpful for deconfliction and reporting
○ Auto populated while operating
○ Agents can report updates or new artifacts
○ Soon include exportability of artifacts to Splunk/SIEMs
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16. COLLABORATIVE
● Web-based GUI
○ No client dependencies besides a modern browser
○ Each operator has their own profile and login
● Users assigned to operations
○ Multiple operations ongoing concurrently
○ Individual tasks sharable amongst team members
● Operators can comment on tasks
○ Seen by all members in that operation
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17. EXTENSIBLE
● You can create/add any number of payload types across all
OSes
○ JXA, Python, C#, Go, etc
○ Can be scripts or compiled
● You can create/add any number of commands for a payload
○ Command templating
● You can create/add/run any number of C2 profiles at a time
○ They run as sub-processes
○ Only bound ports need to be unique
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18. 18
APFELL
Enough words, let’s see Apfell

19. PAYLOAD TYPES
• Add / Edit
Payload types
• Can be wrappers
for full payloads
• Macro
• MSBuild
• DyLib
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20. COMMANDS
• View Code
• Provide operator
help
• Edit code
• Add/edit/remove
parameters
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21. COMMAND TRANSFORMS / ATT&CK /
ARTIFACTS
• Transform
commands
• Provide ATT&CK
Mappings
• Indicate
host/network
artifacts
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22. COMMAND AND CONTROL
PROFILES
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23. C2 PROFILE PARAMETERS
• Specify parameters that will be stamped into an agent during creation
• “key” value is stamped out with user’s value in agent code
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24. PAYLOAD CREATION - UI
• Pick C2 profile, payload type, and initial commands
• Stamp all pieces together
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25. PAYLOAD CONFIGURATION
• All payloads
registered in the
database
• See configuration
and comparison to
server state at any
time
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26. CALLBACK VIEW
• Familiar table of
callbacks like most
tools
• Detailed task data
grouped by task
(not time)
• Add/track optional
comments per task
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27. SHARING SINGULAR TASKS
• Click task number
on almost any page
to view JUST that
one task and its
output
• Easy to share URL
amongst team
members:
/tasks/task#
• Only viewable by
users assigned to
that operation
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28. TASK VIEW
• View all tasks at
once across all
callbacks
• Click to expand
and see output
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29. SEARCH VIEW
• Search all task
output or task
parameters for key
words/phrases
• Searches across
all callbacks in an
operation
• Faster and more
targeted than just 29

30. ATT&CK
× Transform
commands
× Provide ATT&CK
Mappings
× Indicate
host/network
artifacts
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31. APPLY ATT&CK WITH REGEX
• Match all tasks where the parameters fit regex: .*id
• Check matches and their current ATT&CK mappings
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32. BASIC ARTIFACT TRACKING
• Define formats for artifacts based on commands and command
parameters
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33. COMMAND TRANSFORMS
• Toggle transforms on/off locally
• Can optionally persist settings
globally for all operators
• Test outputs of each transform:
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34. UPLOADING / DOWNLOAD
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• View all uploads/downloads and file paths across an operation
• Real-time updates for in-progress downloads

35. SCREEN CAPTURES
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• View screen
captures by
callback or
across an
entire
operation

36. COMMAND COMPLETION
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• Auto populate available
commands based on the
associated payload type for
the callback
• Can use L/R arrow keys to
cycle through choices

37. COMMAND PARAMETERS
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• If a command
has registered
parameters and
you don’t type
any on the
command line
• Pop-up dialog
to fill in
parameters

38. APFELL AGENTS
What does an agent look like?
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39. PAYLOAD DESIGN
CONSIDERATIONS
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● Modular
○ All commands are stand-alone
○ Main payload is just management engine
○ C2 is abstracted away
■ Creates plug-and-play C2 functionality
○ Stamp in commands at creation
■ And load more in later
● Inspiration
○ Malware samples: PlugX, Flame, CozyDuke, etc

40. PAYLOAD DESIGN
CONSIDERATIONS
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● OS Agnostic
○ Apfell is a framework for collaborative operations
○ Payloads can be created for any OS – scripted or compiled
● OPSEC aware
○ Ideally agents track their footprint on host and report back
○ Artifact tracking with real-time data in responses

41. GOING FORWARD
What’s next for Apfell?
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42. FUTURE UPDATES – SHORT TERM
● More encryption
○ Currently just HTTPS
● More payload types across multiple operating systems
○ Python, Mach-O, C#, ELF, Go
● More built-in commands
○ Keylogging, Process Injection, Proxy Pivots
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43. FUTURE UPDATES – MEDIUM TERM
● More customizable C2 profiles included by default
○ Control GET/POST requests
● More C2 profiles that don’t require external comms
○ SMB, SSH
● More Artifact Tracking / Defensive Guidance
○ Better tracking of operational artifacts
○ Inclusion of defensive measures for commands
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44. FUTURE UPDATES – LONG TERM
● Create scriptable Python API for greater control
○ Registerable within the UI – no need for RESTful scripting
● Server speed improvements
○ Automated builds
● More UI Upgrades
○ Attackers think in graphs, not lists
● Community driven updates
○ Please contribute! ☺
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THANKS!Any questions?
• Twitter: @its_a_feature_
• GitHub: github.com/its-a-feature/
• https://its-a-feature.github.io
• Blog series on creating Apfell
• macOS AD discovery (Orchard)
It’s not a bug, it’s a feature