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Overview

uEmu is a tiny cute emulator plugin for IDA based on unicorn engine.

Supports following architectures out of the box: x86, x64, ARM, ARM64, MIPS, MIPS64

What is it GOOD for?

  • Emulate bare metal code (bootloaders, embedded firmware etc)
  • Emulate standalone functions

What is it BAD for?

  • Emulate complex OS code (dynamic libraries, processes etc)
  • Emulate code with many syscalls

What can be improved?

  • Find a way to emulate vendor specific register access (like MSR S3_x, X0 for ARM64)
  • Add more registers to track

Installation

  • Configure IDAPython via idapyswitch
  • brew install unicorn to install Unicorn binaries
  • pip install unicorn to install Unicorn python bindings
  • Use File / Script file... or ALT+F7 in IDA to load uEmu.py

Optionally uEmu can be loaded automatically as IDA plugin. In this case put it into [IDA]/Plugins folder and change USE_AS_SCRIPT to False inside uEmu.py

Features

Popup Menu

  • Start command initializes emulator by mapping all segments and setting up Unicorn
  • Run command emulates instructions until breakpoint is reached or error occurs
  • Step emulates one or N instruction (hold ALT/OPTION to specify a number)
  • Stop interrupts emulation
  • Reset resets emulation engine and unmaps all memory regions
  • Jump To PC simply jumps to current PC
  • Set PC moves PC to cursor
  • It is possible to Update CPU Context manually or via JSON file (see below)
  • Show Controls displays window with Start/Run/Step/Stop buttons
  • Show CPU Context displays window with available registers
  • Show CPU Extended Context displays window with extended registers (FP/SIMD)
  • Show Stack displays window with current Stack
  • Show Memory Range allows to display specific memory region

Start

Start emulation from cursor. It is necessary to provide initial CPU context first (see Update CPU Context) After that all segments from IDA database will be mapped to emulator (initialized data will be copied as well).

Run

Execute code until code or memory breakpoint is reached or there is an event which requires user action.

Step

Perform a single step execution. Hold ALT/OPTION to specify number of steps to perform.

Stop

When emulation is in progress this command can be used to interrupt execution.

Reset

Resets emulator instance and unmaps all memory regions.

Breakpoints

You can use IDA breakpoints to indicate locations where emulation should be interrupted. This includes code and memory breakpoints. Usually used together with Run command.

Runtime actions

Unmapped memory

When emulator needs to access memory which is not yet mapped, plugin will show a following dialog.

  • Press YES to provide memory dump to be loaded to memory.

  • Press NO to map one empty page (0x1000) filled with zeroes
  • Press Cancel to stop emulation

Unknown instructions

When emulator runs into unknown instruction it is possible to skip it and restore CPU context manually.

Views

Controls

Just a panel to control execution.

CPU Context

Current CPU context.

Every time emulation stops, changed registers will be highlighted. Registers can be displayed in 1, 2 or 3 columns via popup menu.

It is possible to update CPU context via popup menu (see below).

CPU Extended Context

Current CPU Extended context.

Every time emulation stops, changed registers will be highlighted. Registers can be displayed in 1, 2 or 3 columns via popup menu.

It is possible to update CPU context via popup menu (see below).

Memory

Use this view to observe memory regions for specified address and size. Comment will be displayed in a title for convenience.

Every time emulation stops, changed memory blocks will be highlighted.

Update CPU Context

Register Values can be changed individually or all at once with JSON file via popup menu. Current context can also be saved in JSON file for future use.

Main Plugin Menu

Apart from all the functions listed in Popup Menu, there are couple of new commands.

Show Mapped Memory

Display all mapped regions. Use popup menu to display memory for particular region or dump it to a file.

Fetch Segments

This command tries to sync IDA segments with mapped memory by creating new mappings or merging with existing ones if possible. This helps to add new IDA segments to emulator in runtime without restarting emulator.

Load Project

Load uEmu state from file.

Save Project

Save uEmu state to file. Please note that only registers defined in a plugin are saved.

Settings

  • Follow PC scrolls IDA View to current PC during emulation
  • Convert to Code automatically is IDA data under cursor is not code
  • Trace instructions prints every instruction emulator is executing
  • Lazy mapping adds pages on demand instead of maping all existing regions on start

Extensions

It is also possible to add new functionality or build your project on top of uEmu using extension system.
Please find description with example here

  • crauEmu - extension for developing and analyzing payloads for code-reuse attacks.