├── LICENSE ├── README.md ├── lineageos_pubkey ├── requirements.txt ├── test_zips ├── README.md ├── base.zip ├── eocd-larger-than-length.zip ├── key ├── multiple-eocd-magics.zip ├── signature-inside-footer.zip ├── signature-larger-than-comment.zip ├── unsigned.zip ├── wrong-eocd-magic.zip └── wrong-footer-magic.zip └── update_verifier.py /LICENSE: -------------------------------------------------------------------------------- 1 | Apache License 2 | Version 2.0, January 2004 3 | http://www.apache.org/licenses/ 4 | 5 | TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 6 | 7 | 1. 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MIIBCgKCAQEApk3T4fhCA4/wP2e46b8JUw/CkTy1PjZUx47CDbyLHnETYoylq8CG 3 | BWDLRCwbUfmLbc5eWcSQN/J/ZPSK7wSQq5kQbwgHohMOGos6rNg05lbwhUtgJne2 4 | bAB7FMLQwo0NxhNB3mSNh521mp554SiIcxo7scYftY9yWsBx3hK2EJPezFaFrCR0 5 | zuLPIvDkS/IIQQ2RxdH2CqeUVUiCK611anDg/hfIPzXl+lm+TdK0RgSPm0IzIYb/ 6 | CqR+05whDen9mBxVcZ7I8wyqxEFcIWBfE/V9Ds3waCxITpRWdI3r6A4vLgsc9H+5 7 | XZL/9Gc+FvY3gfOyx81LkEBBq+td+FBZmQIDAQAB 8 | -----END RSA PUBLIC KEY----- 9 | -------------------------------------------------------------------------------- /requirements.txt: -------------------------------------------------------------------------------- 1 | asn1crypto==1.5.1 2 | cffi==1.17.1 3 | cryptography==43.0.3 4 | pycparser==2.22 5 | -------------------------------------------------------------------------------- /test_zips/README.md: -------------------------------------------------------------------------------- 1 | # Test ZIPs designed to test the asserts 2 | 3 | All are signed with `key` unless otherwise specified 4 | 5 | ## wrong-footer-magic.zip 6 | - Footer magic corrupted 7 | - `footer[2:3] = 0xFF 0xFF` -> `0xFF 0xCC` 8 | 9 | ## signature-larger-than-comment.zip 10 | - Signature start calculated will be larger than the comment 11 | - `footer[0:1] = 0x15 0x06` -> `0xFF 0xFF` 12 | 13 | ## signature-inside-footer.zip 14 | - Signature location appears to be within footer 15 | - `footer[0:1] = 0x15 0x06` -> `0x01 0x00` 16 | - This error can not be reached under any conditions since signature must be 17 | both less than `FOOTER_SIZE` and larger than `comment_size` 18 | 19 | ## eocd-larger-than-length.zip 20 | - Comment size is longer than total length of zip 21 | - `footer[4:5] = 0x27 0x06` -> `0xFF 0xFF` 22 | 23 | ## wrong-eocd-magic.zip 24 | - EOCD has the wrong magic 25 | - `eocd[0:3] = 0x50 0x4B 0x05 0x06` -> `0x50 0x4C 0x05 0x06` 26 | 27 | ## multiple-ecod-magics.zip 28 | - Multiple EOCD magics are present 29 | - `0x50 0x4B 0x05 0x06` inserted 2 bytes after initial EOCD 30 | 31 | # unsigned.zip 32 | - Has not been signed; is a standard zip file 33 | - This will fail on `footer[2:3] != 0xFF 0xFF` 34 | -------------------------------------------------------------------------------- /test_zips/base.zip: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/LineageOS/update_verifier/9ffcf56a0fe152467da2971f0e6b2b79a42f7890/test_zips/base.zip -------------------------------------------------------------------------------- /test_zips/eocd-larger-than-length.zip: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/LineageOS/update_verifier/9ffcf56a0fe152467da2971f0e6b2b79a42f7890/test_zips/eocd-larger-than-length.zip -------------------------------------------------------------------------------- /test_zips/key: -------------------------------------------------------------------------------- 1 | -----BEGIN RSA PUBLIC KEY----- 2 | MIIBCgKCAQEApXq2FOU9MzTqMHuATHvvo9AlgI0IZZ3XOSsWSxzThIrZQxrG95zt 3 | MQS0Wjf5FWe/dt78FA07wCR0QWAOvKxGXDoJoHu0Kpo8cQ9fMsyYV0/3zGUcpTZL 4 | k6635o2tJXsVrFzcEwmZTDTGbmAwN3xTzVeaboa9MCNy8c0btuQga9gCdfuTBrkn 5 | MD1SXZFA2P9alUqb4JQ1ZtTCG5fxwbeBu9KN4bmY4pSMqhM/yc8IzvpiDV99kxRU 6 | xwIMRDTuG0NWTYzAKluZpDJ5BVVEJ1N/jkyYQJcgP4YPkjtfHpUvUUlS9c9Ce2BC 7 | Sa+2rqNQ2rmS36Cl3dWqBNU+vQ8L9IB1KQIDAQAB 8 | -----END RSA PUBLIC KEY----- 9 | -------------------------------------------------------------------------------- /test_zips/multiple-eocd-magics.zip: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/LineageOS/update_verifier/9ffcf56a0fe152467da2971f0e6b2b79a42f7890/test_zips/multiple-eocd-magics.zip -------------------------------------------------------------------------------- /test_zips/signature-inside-footer.zip: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/LineageOS/update_verifier/9ffcf56a0fe152467da2971f0e6b2b79a42f7890/test_zips/signature-inside-footer.zip -------------------------------------------------------------------------------- /test_zips/signature-larger-than-comment.zip: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/LineageOS/update_verifier/9ffcf56a0fe152467da2971f0e6b2b79a42f7890/test_zips/signature-larger-than-comment.zip -------------------------------------------------------------------------------- /test_zips/unsigned.zip: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/LineageOS/update_verifier/9ffcf56a0fe152467da2971f0e6b2b79a42f7890/test_zips/unsigned.zip -------------------------------------------------------------------------------- /test_zips/wrong-eocd-magic.zip: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/LineageOS/update_verifier/9ffcf56a0fe152467da2971f0e6b2b79a42f7890/test_zips/wrong-eocd-magic.zip -------------------------------------------------------------------------------- /test_zips/wrong-footer-magic.zip: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/LineageOS/update_verifier/9ffcf56a0fe152467da2971f0e6b2b79a42f7890/test_zips/wrong-footer-magic.zip -------------------------------------------------------------------------------- /update_verifier.py: -------------------------------------------------------------------------------- 1 | from __future__ import print_function 2 | 3 | from asn1crypto.cms import ContentInfo 4 | from asn1crypto.algos import DigestAlgorithmId 5 | from cryptography.exceptions import InvalidSignature 6 | from cryptography.hazmat.backends import default_backend 7 | from cryptography.hazmat.primitives import hashes 8 | from cryptography.hazmat.primitives.asymmetric import padding 9 | from cryptography.hazmat.primitives.serialization import load_pem_public_key 10 | 11 | import argparse 12 | import os 13 | import sys 14 | import traceback 15 | 16 | FOOTER_SIZE = 6 17 | EOCD_HEADER_SIZE = 22 18 | 19 | 20 | class SignedFile(object): 21 | def __init__(self, filepath): 22 | self._comment_size = None 23 | self._eocd = None 24 | self._eocd_size = None 25 | self._footer = None 26 | self._signed_len = None 27 | self._signature_start = None 28 | self.filepath = filepath 29 | self.length = os.path.getsize(filepath) 30 | 31 | @property 32 | def footer(self): 33 | if self._footer is not None: 34 | return self._footer 35 | with open(self.filepath, 'rb') as zipfile: 36 | zipfile.seek(-FOOTER_SIZE, os.SEEK_END) 37 | self._footer = bytearray(zipfile.read()) 38 | return self._footer 39 | 40 | @property 41 | def comment_size(self): 42 | if self._comment_size is not None: 43 | return self._comment_size 44 | self._comment_size = self.footer[4] + (self.footer[5] << 8) 45 | return self._comment_size 46 | 47 | @property 48 | def signature_start(self): 49 | if self._signature_start is not None: 50 | return self._signature_start 51 | self._signature_start = self.footer[0] + (self.footer[1] << 8) 52 | return self._signature_start 53 | 54 | @property 55 | def eocd_size(self): 56 | if self._eocd_size is not None: 57 | return self._eocd_size 58 | self._eocd_size = self.comment_size + EOCD_HEADER_SIZE 59 | return self._eocd_size 60 | 61 | @property 62 | def eocd(self): 63 | if self._eocd is not None: 64 | return self._eocd 65 | with open(self.filepath, 'rb') as zipfile: 66 | zipfile.seek(-self.eocd_size, os.SEEK_END) 67 | eocd = bytearray(zipfile.read(self.eocd_size)) 68 | self._eocd = eocd 69 | return self._eocd 70 | 71 | @property 72 | def signed_len(self): 73 | if self._signed_len is not None: 74 | return self._signed_len 75 | signed_len = self.length - self.eocd_size + EOCD_HEADER_SIZE - 2 76 | self._signed_len = signed_len 77 | return self._signed_len 78 | 79 | def check_valid(self): 80 | assert self.footer[2] == 255 and self.footer[3] == 255, ( 81 | "Footer has wrong magic") 82 | assert self.signature_start <= self.comment_size, ( 83 | "Signature start larger than comment") 84 | assert self.signature_start > FOOTER_SIZE, ( 85 | "Signature inside footer or outside file") 86 | assert self.length >= self.eocd_size, "EOCD larger than length" 87 | assert self.eocd[0:4] == bytearray([80, 75, 5, 6]), ( 88 | "EOCD has wrong magic") 89 | with open(self.filepath, 'rb') as zipfile: 90 | for i in range(0, self.eocd_size-1): 91 | zipfile.seek(-i, os.SEEK_END) 92 | assert bytearray(zipfile.read(4)) != bytearray( 93 | [80, 75, 5, 6]), ("Multiple EOCD magics; possible exploit") 94 | return True 95 | 96 | def verify(self, pubkey): 97 | self.check_valid() 98 | with open(self.filepath, 'rb') as zipfile: 99 | zipfile.seek(0, os.SEEK_SET) 100 | message = zipfile.read(self.signed_len) 101 | zipfile.seek(-self.signature_start, os.SEEK_END) 102 | signature_size = self.signature_start - FOOTER_SIZE 103 | signature_raw = zipfile.read(signature_size) 104 | sig = ContentInfo.load(signature_raw)['content']['signer_infos'][0] 105 | sig_contents = sig['signature'].contents 106 | sig_type = DigestAlgorithmId.map(sig['digest_algorithm']['algorithm'].dotted) 107 | if sig_type == 'sha256': 108 | hash_algorithm = hashes.SHA256() 109 | elif sig_type == 'sha1': 110 | hash_algorithm = hashes.SHA1() 111 | with open(pubkey, 'rb') as keyfile: 112 | public_key = load_pem_public_key(keyfile.read(), backend=default_backend()) 113 | public_key.verify(sig_contents, message, padding.PKCS1v15(), hash_algorithm) 114 | 115 | 116 | def main(): 117 | parser = argparse.ArgumentParser(description='Verifies whole file signed ' 118 | 'Android update files') 119 | parser.add_argument('public_key') 120 | parser.add_argument('zipfile') 121 | args = parser.parse_args() 122 | 123 | # Enable SHA1 support 124 | os.environ["OPENSSL_ENABLE_SHA1_SIGNATURES"] = "1" 125 | 126 | signed_file = SignedFile(args.zipfile) 127 | try: 128 | signed_file.verify(args.public_key) 129 | print("verified successfully", file=sys.stderr) 130 | except (InvalidSignature, 131 | ValueError, 132 | TypeError, 133 | OSError) as e: 134 | traceback.print_exc() 135 | print("failed verification", file=sys.stderr) 136 | sys.exit(1) 137 | 138 | 139 | if __name__ == '__main__': 140 | main() 141 | --------------------------------------------------------------------------------