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Description

The binwalk python module can be used by any python script to programmatically perform binwalk scans and obtain the results of those scans.

The classes, methods and objects in the binwalk modules are documented via pydoc, including examples, so those interested in using the binwalk module are encouraged to look there. However, several common usage examples are provided here to help jump-start development efforts.

Binwalk Scripting

Each of binwalk's features (signature scans, entropy analysis, etc) are implemented as separate modules. These modules can be invoked via binwalk.scan.

In fact, the binwalk command line utility can be duplicated nearly entirely with just two lines of code:

import binwalk
binwalk.scan()

The scan function accepts both args and kwargs, which correspond to the normal command line options accepted by the binwalk command line utility, providing a large amount of freedom in how you choose to specify binwalk options (if none are specified, sys.argv is used by default).

For example, to execute a signature scan, you at the very least have to specify the --signature option, as well as a list of files to scan. This can be done in a number of ways:

binwalk.scan('--signature', 'firmware1.bin', 'firmware2.bin')

binwalk.scan('firmware1.bin', 'firmware2.bin', signature=True)

binwalk.scan('firmware1.bin', 'firmware2.bin', **{'signature' : True})
        
binwalk.scan(*['firmware1.bin', 'firmware2.bin'], signature=True)
        
binwalk.scan(*['--signature', 'firmware1.bin', 'firmware2.bin',])

All args and kwargs keys/values correspond to binwalk's command line options. Either args or kwargs, or a combination of the two may be used, with the following caveats:

  • All command line switches passed via args must be preceded by hyphens
  • All file names must be passed via args, not kwargs

There is one available API argument which is not exposed via the command line: the string argument. When string is set to True, data to be scanned can be passed directly to the binwalk module, rather than a file name:

data = "This is some data to scan for signatures"
binwalk.scan(data, signature=True, string=True)

Accessing Scan Results

binwalk.scan returns a list of objects. Each object corresponds to a module that was run. For example, if you specified --signature and --entropy, then both the Signature and Entropy modules would be executed and you would be returned a list of two objects.

The two attributes of greatest interest for each object are the results and errors objects. Each is a list of binwalk.core.module.Result and binwalk.core.module.Error instances, respectively. Each Result or Error instance may contain custom attributes set by each module, but are guaranteed to have at least the following attributes (though modules are not required to populate all attributes):

Attribute Description
offset The file offset of the result/error (usually unused for errors)
description The result/error description, as displayed to the user
module Name of the module that generated the result/error
file The file object of the scanned file
valid Set to True if the result is valid, False if invalid (usually unused for errors)
display Set to True to display the result to the user, False to hide it (usually unused for errors)
extract Set to True to flag this result for extraction (not used for errors)
plot Set to False to exclude this result from entropy plots (not used for errors)

binwalk.core.module.Error has the additional guaranteed attribute:

Attribute Description
exception Contains the Python exception object if the encountered error was an exception

Thus, scan results and errors can be programatically accessed rather easily:

for module in binwalk.scan('firmware1.bin', 'firmware2.bin', signature=True, quiet=True):
    print ("%s Results:" % module.name)
    for result in module.results:
        print ("\t%s    0x%.8X    %s" % (result.file.path, result.offset, result.description))

Note the above use of the --quiet option which prevents the binwalk module from printing its normal output to screen.

Each module object will also have an additional extractor attribute, which is an instance of the binwalk.modules.extractor.Extractor class. Of particular use is binwalk.modules.extractor.Extractor.output, a dictionary containing information about carved/extracted data:

for module in binwalk.scan(sys.argv[1], signature=True, quiet=True, extract=True):
    for result in module.results:
        if result.file.path in module.extractor.output:
            # These are files that binwalk carved out of the original firmware image, a la dd
            if result.offset in module.extractor.output[result.file.path].carved:
                print "Carved data from offset 0x%X to %s" % (result.offset, module.extractor.output[result.file.path].carved[result.offset])
            # These are files/directories created by extraction utilities (gunzip, tar, unsquashfs, etc)
            if result.offset in module.extractor.output[result.file.path].extracted:
                print "Extracted %d files from offset 0x%X to '%s' using '%s'" % (len(module.extractor.output[result.file.path].extracted[result.offset].files),
                                                                                  result.offset,
                                                                                  module.extractor.output[result.file.path].extracted[result.offset].files[0],
                                                                                  module.extractor.output[result.file.path].extracted[result.offset].command)

Module Exceptions

The only expected exception that should be raised is that of binwalk.ModuleException. This exception is thrown only if a required module encountered a fatal error (e.g., one of the specified target files could not be opened):

try:
    binwalk.scan()
except binwalk.ModuleException as e:
    print ("Critical failure:", e)
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