Generate hex string yara condition for a function using Radare2

zig2yar.py

# zig2yar
# Copyright (C) 2018 Joakim Kennedy

# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.

# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.

# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

# Install r2pipe with `r2pm -i r2pipe-py`
# Add "$zig2yar=#!pipe python /path/to/zig2yar.py" to .config/radare2/radare2rc
# Run $zig2yar to get a yara signature of the current function.

import r2pipe

r2 = r2pipe.open()

get_offset = str('s')

offset = r2.cmd(get_offset)
fname = r2.cmdj('pdfj @ ' + offset)['name']
zigname = 'zig2yar-' + fname

# Create zignature of the function.
r2.cmd('zaf ' + fname + ' ' + zigname)
zigs = r2.cmdj('zj')
r2.cmd('z-' + zigname)
byte_zig = ''
for zig in zigs:
    if zig['name'] == zigname:
        byte_zig = zig['bytes']
        break

# Convert to yara format
yara = ' '.join([byte_zig[i:i+2] for i in range(0, len(byte_zig), 2)])
print('{ ' + yara.replace('.', '?') + ' }')