zelos package

Module contents

A comprehensive binary emulation platform. <https://github.com/zeropointdynamics/zelos>

class zelos.Zelos(filename, *cmdline_args, **flags)

Bases: object

Class that provides access to the core APIs. These core APIs are event hooking, debugging, memory access, register access, and emulation context.

Parameters

  • filename – Specifies the name of the file to emulate.

  • cmdline_args – Arguments that are passed to the emulated binary.

  • flags – Parameters for zelos. To see the list of all flags, refer to Flags

Example

from zelos import Zelos

# initialize zelos with binary name, 2 cmdline args, and
# verbosity flag set to 1
z = Zelos(
    "binary_to_emulate"
    "ARG1",
    "ARG2",
    verbosity=1,
)
property memory

Returns the MemoryApi object.

property regs

Returns the RegsApi object.

property logger

Returns a logger that will behave in accordance to the –log config/cmdline option.

hook_memory(hook_type: zelos.enums.HookType.MEMORY, callback: Callable[[Zelos, int, int, int, int], Any], mem_low: Optional[int] = None, mem_high: Optional[int] = None, name: Optional[str] = None, end_condition: Optional[Callable[[], bool]] = None) → zelos.hooks.HookInfo

Registers a hook on memory. Executes callback every time the specified event happens in memory.

The hook will only trigger when the event occurs at an address between mem_low and mem_high, if either of them are specified.

The hook will continue to trigger until the end_condition specified evaluates to True.

Parameters

  • hook_type – Specifies the event in memory that should trigger the callback to be executed. Options can be found in zelos.HookType.MEMORY

  • callback – The code that should be executed when the specified event occurs. The function should accept the following inputs: (zelos, access, address, size, value). The return value of “callback” is ignored.

  • mem_low – If specified, only executes callback if the event occurs at an address greater than or equal to this.

  • mem_high – If specified, only executes callback if the event occurs at an address less than or equal to this.

  • name – An identifier for this hook. Used for debugging.

  • end_condition – If specified, executes after the callback. If the function returns True, this hook is deleted.

Returns

Information regarding the hook.

Example

from zelos import Zelos, HookType

# Print every write to memory
def memory_hook(zelos, access, address, size, value):
    print(value)

z = Zelos("binary_to_emulate")
z.hook_memory(
    HookType.MEMORY.WRITE,
    memory_hook
)
z.start()
hook_execution(hook_type: zelos.enums.HookType.EXEC, callback: Callable[[Zelos, int, int], Any], ip_low: Optional[int] = None, ip_high: Optional[int] = None, name: Optional[str] = None, end_condition: Optional[Callable[[], bool]] = None) → zelos.hooks.HookInfo

Registers a hook that executes when code is executed. This is either for every instruction that is executed, or every block.

The hook will only trigger when the event occurs at an address between ip_low and ip_high, if either of them are specified.

The hook will continue to trigger until the end_condition specified evaluates to True.

Parameters

  • hook_type – Specifies whether the callback should be triggered every instruction, or every block. Options can be found in zelos.HookType.EXEC

  • callback – The code that should be executed when the specified event occurs. The function should accept the following inputs: (zelos, address, size). The return value of “callback” is ignored.

  • ip_low – If specified, only executes callback if the event occurs at an address greater than or equal to this.

  • ip_high – If specified, only executes callback if the event occurs at an address less than or equal to this.

  • name – An identifier for this hook. Used for debugging.

  • end_condition – If specified, executes after the callback. If the function returns True, this hook is deleted.

Returns

Information regarding the hook.

Example

from zelos import Zelos, HookType

# Print the first address of every block
def exec_hook(zelos, address, size):
    print(address)

z = Zelos("binary_to_emulate")
z.hook_execution(
    HookType.EXEC.BLOCK, exec_hook
)
z.start()
hook_close(closure: Callable[[], Any]) → zelos.hooks.HookInfo

Registers a closure that is called when zelos.Engine.close() is called.

Parameters

closure – Called when zelos is closed. Does not take any arguments. The return value of closure is ignored

Example

from zelos import Zelos

# Close a file you are using with zelos
file = open("testfile", "r")
def close_cleanup():
    file.close()

z = Zelos("binary_to_emulate")
z.hook_close(close_cleanup)
z.start()

# Hooks are run at this point
z.close()
hook_syscalls(syscall_hook_type: zelos.enums.HookType.SYSCALL, callback: Callable[[Zelos, str, Args, int], Any], name: str = None) → zelos.hooks.HookInfo

Registers a closure that is called when a syscall is invoked.

Parameters

  • syscall_hook_type – Decides when the hook should be triggered in relation to the execution of the syscall. Options can be found in zelos.HookType.SYSCALL

  • callback – The code that should be executed when the specified event occurs. The function should accept the following inputs: (zelos, syscall_name, args, return_value) The return value of “callback” is ignored.

  • name – An identifier for this hook. Used for debugging.

Example

from zelos import Zelos, HookType

# Keep track of the syscall return values
syscall_return_values = []
def syscall_hook(zelos, sys_name, args, ret_val):
    syscall_return_values.append((sys_name, ret_val))

z = Zelos("binary_to_emulate")
z.hook_syscalls(
    HookType.SYSCALL.AFTER, syscall_hook
)
z.start()
delete_hook(hook_info: zelos.hooks.HookInfo) → None
start(timeout: float = 0) → Optional[dict]

Begin emulation. When called for the first time, begins execution at the binary entry point. If the emulation is stopped (for example, after calling stop()) this will resume execution from the current IP.

Parameters

timeout – Stops execution after timeout seconds.

Example

from zelos import Zelos

z = Zelos("binary_to_emulate")

# Start execution from the entry point
z.start()
step(count=1) → None

Begin emulation, stopping after executing count instructions.

Parameters

count – Maximum number of instructions to execute before stopping

next(count=1) → None

Begin emulation, executing count instructions not including instructions inside function calls.

Parameters

count – Maximum number of instructions to execute before stopping.

stop(reason: str = 'plugin')

Stop the Zelos run loop. After a call to stop(), execution can be resumed from the current IP with a call to start().

Parameters

reason – An optional identifier that specifies a reason for stopping execution. Upon calling stop, the reason will be printed to stdout after Zelos exits the run loop. This is useful for debugging when log level is set to ‘debug’ or ‘spam’.

close()

Closes Zelos and runs cleanup functions.

end_thread()

End the current thread. Marks current thread as successfully completed and swaps to the next available thread, if one exists.

swap_thread(reason: str = 'thread swap')

Swap the running thread with the next scheduled thread.

Parameters

reason – An optional identifier that specifies a reason for swapping threads. Upon calling swap_thread, the reason will be printed to stdout after Zelos has successfully swapped to the next scheduled thread. This is useful for debugging when log level is set to ‘spam’.

set_breakpoint(address: int, temporary: bool = False)

Set a breakpoint at a particular address.

Parameters

  • address – Target address of breakpoint.

  • temporary – Determines whether or not the breakpoint is temporary. A temporary breakpoint will be automatically removed after use.

Example

from zelos import Zelos

z = Zelos("binary_to_emulate")

z.set_breakpoint(0xdeadbeef)

z.start()
remove_breakpoint(address: int)

Remove a previously set breakpoint.

Parameters

address – Target address of breakpoint to remove.

Example

from zelos import Zelos

z = Zelos("binary_to_emulate")

z.set_breakpoint(0xdeadbeef)

z.remove_breakpoint(0xdeadbeef)

z.start()
set_syscall_breakpoint(syscall_name: str)

Set a breakpoint at all syscalls of a specified name.

Parameters

syscall_name – Target syscall set breakpoint at.

Example

from zelos import Zelos

z = Zelos("binary_to_emulate")

z.set_syscall_breakpoint("write")

z.start()
remove_syscall_breakpoint(syscall_name: str)

Remove a previously set syscall breakpoint specified by name.

Parameters

syscall_name – Target syscall to remove breakpoints from.

Example

from zelos import Zelos

z = Zelos("binary_to_emulate")

z.set_syscall_breakpoint("write")

z.remove_syscall_breakpoint("write")

z.start()
set_watchpoint(address: int, read: bool, write: bool, temporary: bool = False)

Set a watchpoint on a particular memory address.

Parameters

  • address – Target address of watchpoint.

  • read – Determines whether to watch for reads to the target memory address.

  • write – Determines whether to watch for writes to the target memory address.

Example

from zelos import Zelos

z = Zelos("binary_to_emulate")

# Break at any read or write to memory address 0xdeadbeef
z.set_watchpoint(0xdeadbeef, True, True)

# Break only at writes to memory address 0xfeedf00d
z.set_watchpoint(0xfeedf00d, False, True)

# Break only at reads to memory address 0xb0bad00d
z.set_watchpoint(0xb0bad00d, True, False)

z.start()
remove_watchpoint(address: int)

Remove a previously set watchpoint.

Parameters

address – Target address of watchpoint to remove.

Example

from zelos import Zelos

z = Zelos("binary_to_emulate")

z.set_watchpoint(0xdeadbeef, True, True)

z.remove_watchpoint(0xdeadbeef)

z.start()
property date

Returns the date string used internally during emulation. The date string format is YYYY-MM-DD.

Getter

Returns the date string in YYYY-MM-DD format.

Setter

Sets the date string. Input must be YYYY-MM-DD format.

Type

str

property process

Returns the currently active process.

Type

Process

property thread

Returns the currently active thread.

Type

Thread

property main_binary

Returns the parsed main binary, if it exists, otherwise returns None.

Type

zelos.plugin.ParsedBinary

property main_binary_path

Returns the absolute path to the main binary, if it exists, otherwise returns None.

Type

str

class zelos.ZelosCmdline(cmdline_args)

Bases: zelos.api.zelos_api.Zelos

A workaround for allowing Zelos to be initialized with a commandline string while also allowing the main Zelos to maintain its simple/intuitive constructor based on commandline arguments and flags.

class zelos.MemoryRegion(emu, address: int, size: int, prot: int, name: str, kind: str, module_name: str, shared: bool = False, reserve: bool = False, host_address: int = None, managed_object: any = None)

Bases: object

Represents a region of guest memory.

property start
property end
shrink(address: int, size: int)
get_data() → bytearray

Returns all data in the region.

Returns

Data from the region.

class zelos.Engine(config=None, api=None)

Bases: object

STACK_SIZE = 589824
set_log_level(log_level)
hexdump(address: int, size: int) → None
property current_process
property emu
property memory
property scheduler
property thread_manager
property current_thread
property loader
property modules
property handles
set_mem_limit(limit_in_mb: int) → None
set_writetrace(target)
parse_file(filename)
load_executable(module_path, entrypoint_override=None)

This method simply loads the executable, without starting the emulation

property helpers

Helpers are the first layer in the components hierarchy, which mainly deal with providing help to developers.

load_library(module_name)
disas(address: int, size: int)

Disassemble code at the given address, for up to size bytes

step(count: int = 1) → None

Steps one assembly level instruction

step_over(count: int = 1) → None

Steps on assembly level instruction up to count instructions

start(timeout=0, swap_threads=True) → Optional[dict]

Starts execution of the program at the given offset or entry point.

close() → None

Handles the end of the run command

exception zelos.InvalidHookTypeException

Bases: zelos.exceptions.ZelosException

exception zelos.InvalidRegException

Bases: zelos.exceptions.ZelosException

exception zelos.OutOfMemoryException

Bases: Exception

exception zelos.UnsupportedBinaryError

Bases: zelos.exceptions.ZelosException

exception zelos.ZelosException

Bases: Exception

exception zelos.ZelosLoadException

Bases: zelos.exceptions.ZelosException

exception zelos.ZelosRuntimeException

Bases: zelos.exceptions.ZelosException

class zelos.HookType

Bases: object

class MEMORY

Bases: enum.Enum

Used by zelos.Zelos.hook_memory() to specify the memory event to hook on. View the registration function for more details.

READ = 1
WRITE = 2
READ_UNMAPPED = 3
WRITE_UNMAPPED = 4
READ_PROT = 5
WRITE_PROT = 6
READ_AFTER = 7
UNMAPPED = 8
PROT = 9
READ_INVALID = 10
WRITE_INVALID = 11
INVALID = 12
VALID = 13
class EXEC

Bases: enum.Enum

Used by zelos.Zelos.hook_execution(). If INST is chosen, the registered hook will be executed every time a single instruction is executed.

If BLOCK is chosen, the registered hook will be executed after every block of instructions is executed. A block is interpreted as a contiguous sequence of code where only the last instruction can modify control flow, typically a branch or return instruction.

View the registration function for more details.

INST = 1
BLOCK = 2
class THREAD

Bases: enum.Enum

Not usable yet through Zelos API

CREATE = 1
SWAP = 2
DESTROY = 3
class PROCESS

Bases: enum.Enum

Not usable yet through Zelos API

CREATE = 1
SWAP = 2
DESTROY = 3
class SYSCALL

Bases: enum.Enum

Used by zelos.Zelos.hook_syscalls().

If AFTER is chosen, the hook will be triggered after the syscall hass been executed.

View the registration function for more details.

AFTER = 1
class zelos.ProtType

Bases: enum.IntEnum

An enumeration.

NONE = 0
READ = 1
WRITE = 2
EXEC = 4
RWX = 7
RX = 5
RW = 3
class zelos.CommandLineOption(name, **kwargs)

Bases: object

Registers a command line option for Zelos. The kwargs are those recognized by the argparse library

class zelos.IPlugin(zelos)

Bases: zelos.manager.IManager

Base class for Plugins that provides an api for interacting with zelos objects.

class zelos.ISubcommand(argparser)

Bases: object