Post on 22-Jan-2016
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VMM Based Rootkit Detection on Android
Class PresentationPete Bohman, Adam Kunk, Erik Shaw
Motivation
The Increase of Mobile Malware Variants (2004 – 2010)
• Smartphone malware on the rise• Increased security implications (compared to PC)• Sensitive information: GPS, contacts, SMS, call log• Constantly connected• Naïve users, limited use of Anti Virus
Defensive Rootkit Approaches• User mode rootkits
– Process infection, binary patching, lib hooks
• User mode integrity checkers– tripwire, chkrootkit, rkthunter, AV scanner
• Kernel mode rootkits– malicious device drivers and lkms– sys call hooking, kernel data structure manipulation
• Kernel level inspection– behavioral analysis, data structure integrity checkers, hook detection
• But… Any kernel level inspection mechanisms can be subverted by kernel level rootkits
Our Approach
• Two Pronged• KM security mechanisms • System call integrity checks• Hidden process detection• Android capability table
• VMM inspection • Ensures integrity of static KM• Isolated from host OS
• We exercise a “layer-below” level of security in which we establish trust beneath the kernel
Android Software Stack
Solution Preview (Delete Slide)Android Software Stack
Android VMM ensures integrity of static kernel module
Kernel module implements security mechanisms
Overview
• Design• VMM Design• Protected KM Design• Implementation• Results• Demo Presentation• Conclusion• Q&A
VMM Interface Design
Android VMM
Hardware (Emulator)
Linux Kernel
Trusted KM <ISR>
Libraries and Runtime
Application Framework
1. Hardware Timer Interrupt
2. Validate Protected KM 3. Raise Monitor Interrupt
4. Invoke KM
Protection KM Design
Linux KernelTrusted KMSystem Call WhitelistOriginal Sys Call Table
Libraries and Runtime
Maps
Application Framework
Contacts SMS App
Content Provider
Location Provider
Activity Manager
Open
Malicious Native
ApplicationSystem Calls
Open SocketRead GPSSQL QuerySysCall Table
…
Protection KM Design
Linux KernelTrusted KMSystem Call WhitelistOriginal Sys Call Table
Libraries and Runtime
X
MaliciousLKM
System Calls
SysCall Table
Y Z<ISR>
Android VMM
Monitor Interrupt
Implementation
• Implemented VMM security functionality in an emulated hardware device within QEMU• Protected KM data and text compiled into QEMU
emulator (VMM)
Linux Kernel Source with
Protection KMCompilation
Kernel Image
Protected Text Sect.
Protected Data Sect.
QEMU Emulator(VMM) Compilation
QEMU Emulator(VMM)Protected TextProtected Data
Implementation
• Malicious native mode application• Read contacts database• Read GPS location• Ex-filled data using sockets
• Malicious LKM• Intercept read system calls to access GPS location
Results
• We are able to detect/correct modifications to the sys_call_table• We are able to prevent malicious access to sensitive
resources• TODO Mention Malicious App and LKM
• TODO: (Insert link to demo)
Conclusion
• Layer Below Protection• Security of the Linux kernel must be rooted in a layer
below the kernel• Code contained solely in the kernel is subject to any
kernel-level attack
• Sensitive Resource Protection• Android mobile phones contain lots of sensitive
information that must be protected
App PermissionsDalvik VM IsolationApp signatures
Limits application abilities in order to prevent malicious behavior.
Virus ScannersRemote Lockout
Modified system binariesTrojan’d servicesStolen device
Linux user and group permissions
Access control
Architecture Layer Security Mechanism Threat Mitigation
Linux Kernel Source with
Protection KMCompilation
Kernel Image
Protected Text Sect.
Protected Data Sect.
QEMU Emulator(VMM) Compilation
QEMU Emulator(VMM)Protected TextProtected Data
Problem Statement
• Rootkit detection and prevention on the Android platform with specific regards to the sensitive resources Android provides.• Kapersky 2011: 1046 unique malware strains
targeting mobile platforms• Android platform built on Linux Kernel, a well known
target.• Sensitive information on smart phones• GPS, contacts, text messages, call log