214 lines
9.0 KiB
Plaintext
214 lines
9.0 KiB
Plaintext
I. Introduction
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A. Who are we?
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1. spoonm
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2. skape
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B. Exploit Technology
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1. Three Phases of Exploitation
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a. Pre-exploitation
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b. Exploitation
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c. Post-exploitation
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2. Pre-exploitation - Preparing the payload
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a. NOP generation
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b. Payload encoders
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c. Connection handler initialization
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3. Exploitation - Leveraging the vulnerability
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a. Stack overflows
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c. Heap overflows
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b. SEH overwrites
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d. Arbitrary pointer overwrites
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4. Post-Exploitation - Manipulating the target
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a. Command shell redirection
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b. Arbitrary command execution
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c. Pivoting payloads
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d. Advanced payload interaction
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B. Where do we stand?
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1. Pre-exploitation
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a. Robust and elegant encoders do exist
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i. SkyLined's alpha-numeric encoder
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ii. Spoonm's Shikata Ga Nai
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b. Payload encoders generally taken for granted
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i. Most encoders are static with a variable key
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ii. IDS able to signature static decoder stubs
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c. NOP generation hasn't publically changed much
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i. PoC exploits generally use predictable nops, if any
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ii. ADMmutate easily signatured by most NIDS (Snort, Fnord)
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iii. Not considered very important to many researchers
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d. NIDS deployments are playing chase the tail
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i. The mouse always has the advantages; NIDS is reactive
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ii. Advanced nops and encoders push NIDS to its limits
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2. Exploitation
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a. Techniques have become very mature
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i. Linux/BSD exploitation techniques largely unchanged
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ii. Win32 heap overflows now more reliable (oded/shok)
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iii. Win32 SEH overwrites make exploitation easy, even on XPSP2
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b. Exploitation topics have been beaten to death
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3. Post-exploitation
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a. Common payloads are limited
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i. Command shell interaction has poor automation support
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ii. Limited to the command set that the interpreter provides
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iii. Bounded by the utilities installed on the target machine
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iv. Restrictive environments (chroot) can hinder command execution
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v. HIPS vendors becoming more adept at detecting basic payloads
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- LoadLibraryA from the stack, etc (mcafee 8.0i)
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b. Communication vectors largely unchanged
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i. Reverse and port-bind payloads still the most common
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ii. Findsock style payloads still unused PoC exploits
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iii. Alternative communication vectors rarely discussed
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b. Pivoting technology exists
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i. Core ST described system call proxying in 2002
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ii. Metasploit's (2.3) meterpreter provides basic network pivoting
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C. What will we discuss?
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1. Pre-exploitation Research
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a. NOP generation
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i. Opty2
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b. Encoders
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i. Additive feedback encoders
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ii. Shikata Ga Nai
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2. Post-Exploitation Research
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a. Library Injection
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i. Facilitates things like Meterpreter and VNC injection
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b. VNC Injection
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i. Introduced at blackhat04 with the Metasploit 2.2 release
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c. Meterpreter & dN
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i. The cross-platform post-exploitation suite
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3. Payload Research
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a. PassiveX
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b. Ordinal Stagers
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c. Egghunt (maybe?)
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II. Pre-exploitation
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A. Opty2
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1. spoonfu
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B. Additive feedback encoders
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C. Shikata Ga Nai
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1. spoonfu
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III. Post-exploitation
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A. Library Injection
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1. Provides advanced code execution
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a. Code can be written in any language that can compile down
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to a shared object.
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b. Allows developer to use all of the APIs exposed to a normal
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application.
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2. Two types of library injection
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a. On-Disk
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i. Library is loaded from the target's harddrive or via a
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file share.
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b. In-Memory
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i. Library is uploaded to the target and loaded from memory
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without touching the disk
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ii. Evades file system filter drivers, such as those
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provided by AV companies
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iii. Not touching the disk means no forensic trace
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B. VNC Injection
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1. Implements VNC as an injectable DLL
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a. Uses RealVNC as the code-base
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b. VNC communication uses the exploit connection
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c. No physical trace is left of the VNC server
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d. Can operate regardless of existing VNC installations
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2. Easy way to illustrate insecurities
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a. Suits understand mouse movement better than black box command
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prompts
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C. Meterpreter
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1. Generic post-exploitation suite
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a. Based on library injection
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b. Uses the established exploit connection
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i. Especially powerful with findsock payloads; no new connection
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c. Executes entirely from memory
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d. No new processes or file access required for the payload to
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succeed
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2. Extension system provides advanced automation support
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a. No need to hand write tedious assembly
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b. Existing native code can be ported to a meterpreter extension
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3. Architecture
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a. Design goals
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i. Very flexible protocol; should adapt to extension requirements
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ii. Exposure of a channelized communication system to extensions
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iii. Stealth operation
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iv. Should be portable to various operating systems
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v. Client from one platform should work with server on another
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platform
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b. Protocol
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i. Uses TLVs (Type-Length-Value) to support arbitrary data
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passing.
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ii. TLVs allow the packet parser to be oblivious to the structure
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of the value field
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iii. Type field is broken down into meta types
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4. Core interface
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a. Overview
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i. Minimal interface to support the loading of extensions
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ii. Implements the basic packet transmission and dispatching
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facilities
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iii. Exposes channel allocation and management to extensions
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b. Advanced features
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i. Migrating the server instance between processes
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5. The ``stdapi'' extension
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a. Overview
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i. Included in Metasploit 3.0
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ii. Provides access to some of the common facilities of the
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target operating system
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iii. Allows for easy automation and implementation of robust
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post-exploitation scripts
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b. File System
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i. File and directory interaction
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ii. Files can be uploaded and downloaded between the
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attacker and the target
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c. Network
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i. Transparent network pivoting
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ii. Route table enumeration and manipulation
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iii. Local interface enumeration
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d. Process
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i. Process execution, optionally with channelized IO
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ii. Enumeration of running processes
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iii. Modification of arbitrary memory
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iv. Creation and modification of running threads
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v. Loading and interacting with shared object files
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e. Registry
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i. General registry API access
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ii. Opening, creating, and removing registry keys
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iii. Setting, querying, and deleting registry values
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iv. Enumeration of both keys and values
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f. User interface
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i. Disabling local user interaction via the keyboard
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and/or mouse (similar to VNC)
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ii. Idle timeout checking to see how long it's been
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since the user did something interactive
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6. The ``priv'' extension
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a. Still in development
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b. Exposes an interface to escalating local privileges
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through local vulnerabilities
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c. SAM dumping support similar to pwdump3
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D. dN
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1. spoonfu
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E. PassiveX
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1. Overview
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a. Post-exploitation payload
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b. A derivative of On-Disk library injection that uses
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ActiveX controls
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2. Implementation
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a. Disables iexplore Internet zone restrictions on
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ActiveX controls
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b. Launches a hidden iexplore at a URL with an embedded
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OCX
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c. ActiveX control restores zone restrictions
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X. talk about socketpair tcp abstraction
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talk about http tunneling
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4. Pros
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a. Bypasses restrictive outbound filters
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b. Re-uses proxy configuration
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c. Looks like normal user traffic
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5. Cons
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a. Touches the disk
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b. Requires administrative access
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i. Internet Explorer prohibits the downloading of
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ActiveX controls as non-admin
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IV. The Complete Picture
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A. Show how powerful msf3 is here
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V. Conclusion - where do we go from here?
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cite:
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STRIDE:
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http://www.ics.forth.gr/carv/acs/ACS/Activities/papers/stride-IFIP-SEC05.pdf
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syscall proxy:
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http://www.coresecurity.com/files/files/11/SyscallProxying.pdf
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