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ADVANCED_USE.md

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Avanced use

Architecture selection

The architecture might be automatically recognized from the binary (for instance, using ELF or PE information).

If not, the architecture can be specified / forced using the --architecture argument of find.

Mapping shift

It may happens that the file format is not correctly recognized (for instance, in firmware), and that having the binary mapped at a specific address modify the function behavior (ie. they use absolute address).

For these cases, the option --mapping-base can be used to specify a base address for the binary mapping.

Emulation engine

A few emulation engine are supported. Through the --jitter option, one can specified:

  • python: use a full Python emulation
  • tcc or gcc: use a C compiler to JiT code (thanks to Miasm)
  • LLVM: use LLVM JiT capabilities (thanks to Miasm)
  • qemu: use the Unicorn (http://www.unicorn-engine.org/) QEMU binding

Empirically, the qemu jitter happens to be the fastest, but requires an additionnal dependency. In addition, it may not support a custom architecture added to Miasm.

The second fastest jitter is gcc, because of the repeated call to the same function (and its cache). In addition, it requires a very common dependency.

Function heuristic

The sibyl func action provides a way to find possible function addresses. It uses heuristics, which can be individually activated or de-activated using -e and -d options.

For instance, the recursive_call heuristics may take a long time to ends, where the pattern_matching one is very fast but innacurate.

The full list can be obtain in the --help description.

As a side note, a common, dirty, way to obtain function addresses is to use the following one-liner in IDA console:

open("/tmp/addrs", "w").write("\n".join(hex(x).replace("L", "") for x in Functions()))

Addresses specification

The targeted addresses can be specified in three ways:

  • using the addresses, such as sibyl find my_binary 0x11223344 0x22334455 12345
  • using a file, such as sibyl find my_binary /tmp/addrs
  • using stdin, such as sibyl func my_binary | sibyl find my_binary -

ABI selection

The ABI can be specified or overwritten thanks to the --abi option of sibyl find.

If only one ABI is available for the target architecture, it will be selected automatically. Otherwise, the command line will ask for more precision.

The choosen ABI is indicated if the verbosity level is high enough.

Linking with other tools

Sibyl output is intended to be human readable.

But, depending on the usage, some options are provided for an easier linking:

  • sibyl find can deliver results in JSON format (-o JSON)
  • sibyl config can be requested for direct value, or possible value of a configuration element (-V element)
  • the sibyl module can be used as an API