B::Deobfuscate - Deobfuscate source code
perl -MO=Deobfuscate,-csynthetic.yml,-y synthetic.pl
B::Deobfuscate is a backend module for the Perl compiler that generates perl
source code, based on the internal compiled structure that perl itself creates
after parsing a program. It adds symbol renaming functions to the B::Deparse
module. An obfuscated program is already parsed and interpreted correctly by
the B::Deparse program. Unfortunately, if the obfuscation involved variable
renaming then the resulting program also has obfuscated symbols.
This module takes the last step and fixes names like
$z5223ed336 to be a word from a dictionary. While
the name still isn't meaningful it is at least easier to distinguish and
read. Here are two examples - one from B::Deparse and one from
B::Deobfuscate.
Initial input
if(@z6a703c020a){(my($z5a5fa8125d,$zcc158ad3e0)=File::Temp::tempfile(
'UNLINK',1));print($z5a5fa8125d "=over 8\n\n");(print($z5a5fa8125d
@z6a703c020a)or die(((("Can't print $zcc158ad3e0: $!"))); print($z5a5fa8125d
"=back\n");(close(*$z5a5fa8125d)or die(((("Can't close ".*$za5fa8125d.": $!")
));(@z8374cc586e=$zcc158ad3e0);($z9e5935eea4=1);}
After B::Deparse:
if (@z6a703c020a) {
(my($z5a5fa8125d, $zcc158ad3e0) = File::Temp::tempfile('UNLINK', 1));
print($z5a5fa8125d "=over 8\n\n");
(print($z5a5fa8125d @z6a703c020a)
or die((((q[Can't print ] . $zcc158ad3e0) . ': ') . $!)));
print($z5a5fa8125d "=back\n");
(close(*$z5a5fa8125d)
or die((((q[Can't close ] . *$za5fa8125d) . ': ' . $!)));
(@z8374cc586e = $zcc158ad3e0);
($z9e5935eea4 = 1);
}
After B::Deobfuscate:
if (@parenthesises) {
(my($scrupulousity, $postprocesser) = File::Temp::tempfile('UNLINK', 1));
print($scrupulousity "=over 8\n\n");
(print($scrupulousity @parenthesises)
or die((((q[Can't print ] . $postprocesser) . ': ') . $!)));
print($scrupulousity "=back\n");
(close(*$scrupulousity)
or die((((q[Can't close ] . *$postprocesser) . ': ') . $!)));
(@interruptable = $postprocesser);
($propagandaist = 1);
}
You'll note that the only real difference is that instead of
variable names like $z9e5935eea4 you get
$propagandist.
As with all compiler backend options, these must follow directly after the
'-MO=Deobfuscate', separated by a comma but not any white space. All options
defined in B::Deparse are supported here - see the B::Deparse documentation
page to see what options are provided and how to use them.
- -dDICTIONARY FILE
- Normally B::Deobfuscate reads an internal dictionary of easily pronounced
keywords. If you would like to specify a different dictionary follow the
-d parameter with the path to the dictionary file. The path may not have
commas in it and only lines in the dictionary that do not match /\W/ will
be used. The entire dictionary will be loaded into memory at once.
-d/usr/share/dict/stop
- -DB::Deobfuscate::Dict:: module
- B::Deobfuscate defaults to using the dictionary at
B::Deobfuscate::Dict::PGPHashWords. You can ask it to load any other
module under the B::Deobfuscate::Dict:: namespace by using the
"-D..." parameter.
B::Deobfuscate 0.14 and above is distributed with the
additional dictionary B::Deobfuscate::Dict::Flowers.
- -mREGEX
- Supply a different regular expression for deciding which symbols to
rename. The default value is /\A[[:lower:][:digit:]_]+\z/. Your expression
must be delimited by the '/' characters and you may not use that character
within the expression. That shouldn't be an issue because '/' isn't valid
in a symbol name anyway.
-a/\A[[:lower:][:digit:]_]+\z/
- -y
- print two YAML documents to STDOUT instead of the deparsed source
code. The first document is a configuration document suitable for use with
the -c parameter. The second document is the deparsed source code.
Use this feature to generate a configuration document for further,
iterative reverse engineering.
The intention here is that you could write some software to
read this YAML document, present the information to the user, accept
some alterations to the configuration and re-run the deobfuscator with
the new input.
- -cFILENAME
- Supply a filename to a YAML configuration file. Normally you would
generate this file by saving the results of the -y parameter to a
file. You can then edit the file to provide your own names for symbols and
not rely on the random symbol picker in B::Deobfuscate. You may
create your own YAML configuration file as well.
The B::Deobfuscation symbol renamer can be controlled with by a configuration
file. Use of this feature requires the YAML module be installed.
dictionary: '/usr/share/dict/propernames'
global_regex: '(?:)'
globals:
kSDsfDS: Slartibartfast
HGFdsfds: Triantaphyllos
lexicals:
'$SdfSd': '$No'
'$GsdDd': '$Ed'
'$Ksdfs': '$Ji'
- dictionary
- This is a filename path to the operative dictionary.
dictionary: /usr/share/dict/stop
- global_regex
- This regular expression tests global symbols. Only symbols that match this
expression may be renamed. The default value is
'\A[[:lower:][:digit:]_]\z/. In perl, global symbols are independent of
their sigil so the values being tested are bare. Future versions of
B::Deobfuscate may add the sigil to the symbol name.
global_regex: '\A[[:lower:][:digit:]_]\z'
- globals
- This is a hash detailing symbol names as used in the original source and
the name used in the deobfuscated source. For example - if the original
source has a variable named @z12345 and you wish
to rename all occurrances to @URLList then the
hash would associate 'z12345' with 'URLList'. The dictionary picker fills
these values in automatically.
If you wish to prevent B::Deobfuscate from renaming a symbol
then specify the new value as '~' (which in YAML terms is undef).
globals:
catfile: ~
opt_n: ~
opt_t: ~
opt_u: ~
z1234567890: Postprocesser
z2345678901: Constructable
z3456789012: Photosynthesises
z4567890123: Undiscriminate
z5678901234: Parenthesises
z6789012345: Animadvertion
- lexicals
- Lexicals is a hash exactly like `globals' except that all the symbol names
include the sigil which doesn't currently happen for globals.
lexicals:
'$k1234567890': '$ivs'
'$k2345678901': '$ehs'
'$k3456789012': '$ans'
'$k4567890123': '$ons'
'$k5678901234': '$ofs'
'$k6789012345': '$gos'
'$k7890123456': '$dus'
'$k8901234567': '$iis'
'$k9012345678': '$ats'
'$k0123456780': '$ets'
Joshua ben Jore <jjore@cpan.org>
B::Deparse <http://www.perlmonks.org/index.pl?node_id=243011>
<http://www.perlmonks.org/index.pl?node_id=244604> YAML