1// Copyright 2014 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#include "components/os_crypt/ie7_password_win.h"
6
7#include <wincrypt.h>
8#include <string>
9#include <vector>
10
11#include "base/memory/scoped_ptr.h"
12#include "base/sha1.h"
13#include "base/strings/string_util.h"
14#include "base/strings/stringprintf.h"
15
16namespace {
17
18// Structures that IE7/IE8 use to store a username/password.
19// Some of the fields might have been incorrectly reverse engineered.
20struct PreHeader {
21  DWORD pre_header_size;  // Size of this header structure. Always 12.
22  DWORD header_size;      // Size of the real Header: sizeof(Header) +
23                          // item_count * sizeof(Entry);
24  DWORD data_size;        // Size of the data referenced by the entries.
25};
26
27struct Header {
28  char wick[4];             // The string "WICK". I don't know what it means.
29  DWORD fixed_header_size;  // The size of this structure without the entries:
30                            // sizeof(Header).
31  DWORD item_count;         // Number of entries. Should be even.
32  wchar_t two_letters[2];   // Two unknown bytes.
33  DWORD unknown[2];         // Two unknown DWORDs.
34};
35
36struct Entry {
37  DWORD offset;         // Offset where the data referenced by this entry is
38                        // located.
39  FILETIME time_stamp;  // Timestamp when the password got added.
40  DWORD string_length;  // The length of the data string.
41};
42
43// Main data structure.
44struct PasswordEntry {
45  PreHeader pre_header;  // Contains the size of the different sections.
46  Header header;         // Contains the number of items.
47  Entry entry[1];        // List of entries containing a string. Even-indexed
48                         // are usernames, odd are passwords. There may be
49                         // several sets saved for a single url hash.
50};
51}  // namespace
52
53namespace ie7_password {
54
55bool GetUserPassFromData(const std::vector<unsigned char>& data,
56                         std::vector<DecryptedCredentials>* credentials) {
57  const PasswordEntry* information =
58      reinterpret_cast<const PasswordEntry*>(&data.front());
59
60  // Some expected values. If it's not what we expect we don't even try to
61  // understand the data.
62  if (information->pre_header.pre_header_size != sizeof(PreHeader))
63    return false;
64
65  const int entry_count = information->header.item_count;
66  if (entry_count % 2)  // Usernames and Passwords
67    return false;
68
69  if (information->header.fixed_header_size != sizeof(Header))
70    return false;
71
72  const uint8* offset_to_data = &data[0] +
73                                information->pre_header.header_size +
74                                information->pre_header.pre_header_size;
75
76  for (int i = 0; i < entry_count / 2; ++i) {
77
78    const Entry* user_entry = &information->entry[2*i];
79    const Entry* pass_entry = user_entry+1;
80
81    DecryptedCredentials c;
82    c.username = reinterpret_cast<const wchar_t*>(offset_to_data +
83                                                  user_entry->offset);
84    c.password = reinterpret_cast<const wchar_t*>(offset_to_data +
85                                                  pass_entry->offset);
86    credentials->push_back(c);
87  }
88  return true;
89}
90
91std::wstring GetUrlHash(const std::wstring& url) {
92  std::wstring lower_case_url = base::StringToLowerASCII(url);
93  // Get a data buffer out of our std::wstring to pass to SHA1HashString.
94  std::string url_buffer(
95      reinterpret_cast<const char*>(lower_case_url.c_str()),
96      (lower_case_url.size() + 1) * sizeof(wchar_t));
97  std::string hash_bin = base::SHA1HashString(url_buffer);
98
99  std::wstring url_hash;
100
101  // Transform the buffer to an hexadecimal string.
102  unsigned char checksum = 0;
103  for (size_t i = 0; i < hash_bin.size(); ++i) {
104    // std::string gives signed chars, which mess with StringPrintf and
105    // check_sum.
106    unsigned char hash_byte = static_cast<unsigned char>(hash_bin[i]);
107    checksum += hash_byte;
108    url_hash += base::StringPrintf(L"%2.2X", static_cast<unsigned>(hash_byte));
109  }
110  url_hash += base::StringPrintf(L"%2.2X", checksum);
111
112  return url_hash;
113}
114
115bool DecryptPasswords(const std::wstring& url,
116                      const std::vector<unsigned char>& data,
117                      std::vector<DecryptedCredentials>* credentials) {
118  std::wstring lower_case_url = base::StringToLowerASCII(url);
119  DATA_BLOB input = {0};
120  DATA_BLOB output = {0};
121  DATA_BLOB url_key = {0};
122
123  input.pbData = const_cast<unsigned char*>(&data.front());
124  input.cbData = static_cast<DWORD>((data.size()) *
125                                    sizeof(std::string::value_type));
126
127  url_key.pbData = reinterpret_cast<unsigned char*>(
128                      const_cast<wchar_t*>(lower_case_url.data()));
129  url_key.cbData = static_cast<DWORD>((lower_case_url.size() + 1) *
130                                      sizeof(std::wstring::value_type));
131
132  if (CryptUnprotectData(&input, NULL, &url_key, NULL, NULL,
133                         CRYPTPROTECT_UI_FORBIDDEN, &output)) {
134    // Now that we have the decrypted information, we need to understand it.
135    std::vector<unsigned char> decrypted_data;
136    decrypted_data.resize(output.cbData);
137    memcpy(&decrypted_data.front(), output.pbData, output.cbData);
138
139    GetUserPassFromData(decrypted_data, credentials);
140
141    LocalFree(output.pbData);
142    return true;
143  }
144
145  return false;
146}
147
148}  // namespace ie7_password
149