Office Application Initiated Network Connection To Non-Local IP

calendar Aug 12, 2024 · attack.execution attack.t1203  ·
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Detects an office application (Word, Excel, PowerPoint) that initiate a network connection to a non-private IP addresses. This rule aims to detect traffic similar to one seen exploited in CVE-2021-42292. This rule will require an initial baseline and tuning that is specific to your organization.

Sigma rule (View on GitHub)

  1title: Office Application Initiated Network Connection To Non-Local IP
  2id: 75e33ce3-ae32-4dcc-9aa8-a2a3029d6f84
  3status: test
  4description: |
  5    Detects an office application (Word, Excel, PowerPoint)  that initiate a network connection to a non-private IP addresses.
  6    This rule aims to detect traffic similar to one seen exploited in CVE-2021-42292.
  7    This rule will require an initial baseline and tuning that is specific to your organization.    
  8references:
  9    - https://corelight.com/blog/detecting-cve-2021-42292
 10    - https://learn.microsoft.com/de-de/microsoft-365/enterprise/urls-and-ip-address-ranges?view=o365-worldwide
 11author: Christopher Peacock '@securepeacock', SCYTHE '@scythe_io', Florian Roth (Nextron Systems), Tim Shelton, Nasreddine Bencherchali (Nextron Systems)
 12date: 2021-11-10
 13modified: 2024-07-02
 14tags:
 15    - attack.execution
 16    - attack.t1203
 17logsource:
 18    category: network_connection
 19    product: windows
 20detection:
 21    selection:
 22        Image|endswith:
 23            - '\excel.exe'
 24            - '\outlook.exe'
 25            - '\powerpnt.exe'
 26            - '\winword.exe'
 27            - '\wordview.exe'
 28        Initiated: 'true'
 29    filter_main_local_ranges:
 30        DestinationIp|cidr:
 31            - '127.0.0.0/8'
 32            - '10.0.0.0/8'
 33            - '172.16.0.0/12'
 34            - '192.168.0.0/16'
 35            - '169.254.0.0/16'
 36            - '::1/128'  # IPv6 loopback
 37            - 'fe80::/10'  # IPv6 link-local addresses
 38            - 'fc00::/7'  # IPv6 private addresses
 39    filter_main_msrange_generic:
 40        DestinationIp|cidr:
 41            - '20.184.0.0/13' # Microsoft Corporation
 42            - '20.192.0.0/10' # Microsoft Corporation
 43            - '23.72.0.0/13' # Akamai International B.V.
 44            - '40.76.0.0/14' # Microsoft Corporation
 45            - '51.10.0.0/15' # Microsoft Corporation
 46            - '51.103.0.0/16' # Microsoft Corporation
 47            - '51.104.0.0/15' # Microsoft Corporation
 48            - '51.142.136.0/22' # Microsoft Corporation - https://ipinfo.io/AS8075/51.140.0.0/14-51.142.136.0/22
 49            - '52.160.0.0/11' # Microsoft Corporation - https://ipinfo.io/AS8075/52.160.0.0/11
 50            - '204.79.197.0/24' # Microsoft Corporation
 51    filter_main_msrange_exchange_1:
 52        # Exchange Online
 53        # "urls": [
 54        #       "outlook.cloud.microsoft",
 55        #       "outlook.office.com",
 56        #       "outlook.office365.com"
 57        # ]
 58        DestinationIp|cidr:
 59            - '13.107.6.152/31'
 60            - '13.107.18.10/31'
 61            - '13.107.128.0/22'
 62            - '23.103.160.0/20'
 63            - '40.96.0.0/13'
 64            - '40.104.0.0/15'
 65            - '52.96.0.0/14'
 66            - '131.253.33.215/32'
 67            - '132.245.0.0/16'
 68            - '150.171.32.0/22'
 69            - '204.79.197.215/32'
 70            - '2603:1006::/40'
 71            - '2603:1016::/36'
 72            - '2603:1026::/36'
 73            - '2603:1036::/36'
 74            - '2603:1046::/36'
 75            - '2603:1056::/36'
 76            - '2620:1ec:4::152/128'
 77            - '2620:1ec:4::153/128'
 78            - '2620:1ec:c::10/128'
 79            - '2620:1ec:c::11/128'
 80            - '2620:1ec:d::10/128'
 81            - '2620:1ec:d::11/128'
 82            - '2620:1ec:8f0::/46'
 83            - '2620:1ec:900::/46'
 84            - '2620:1ec:a92::152/128'
 85            - '2620:1ec:a92::153/128'
 86        DestinationPort:
 87            - 80
 88            - 443
 89    filter_main_msrange_exchange_2:
 90        # Exchange Online
 91        # "urls": [
 92        #       "outlook.office365.com",
 93        #       "smtp.office365.com"
 94        # ]
 95        DestinationIp|cidr:
 96            - '13.107.6.152/31'
 97            - '13.107.18.10/31'
 98            - '13.107.128.0/22'
 99            - '23.103.160.0/20'
100            - '40.96.0.0/13'
101            - '40.104.0.0/15'
102            - '52.96.0.0/14'
103            - '131.253.33.215/32'
104            - '132.245.0.0/16'
105            - '150.171.32.0/22'
106            - '204.79.197.215/32'
107            - '2603:1006::/40'
108            - '2603:1016::/36'
109            - '2603:1026::/36'
110            - '2603:1036::/36'
111            - '2603:1046::/36'
112            - '2603:1056::/36'
113            - '2620:1ec:4::152/128'
114            - '2620:1ec:4::153/128'
115            - '2620:1ec:c::10/128'
116            - '2620:1ec:c::11/128'
117            - '2620:1ec:d::10/128'
118            - '2620:1ec:d::11/128'
119            - '2620:1ec:8f0::/46'
120            - '2620:1ec:900::/46'
121            - '2620:1ec:a92::152/128'
122            - '2620:1ec:a92::153/128'
123        DestinationPort:
124            - 143
125            - 587
126            - 993
127            - 995
128        Protocol: 'tcp'
129    filter_main_msrange_exchange_3:
130        # Exchange Online
131        # "urls": [
132        #       "*.protection.outlook.com"
133        #  ]
134        DestinationIp|cidr:
135            - '40.92.0.0/15'
136            - '40.107.0.0/16'
137            - '52.100.0.0/14'
138            - '52.238.78.88/32'
139            - '104.47.0.0/17'
140            - '2a01:111:f400::/48'
141            - '2a01:111:f403::/48'
142        DestinationPort: 443
143    filter_main_msrange_exchange_4:
144        # Exchange Online
145        # "urls": [
146        #       "*.mail.protection.outlook.com",
147        #       "*.mx.microsoft"
148        #  ]
149        DestinationIp|cidr:
150            - '40.92.0.0/15'
151            - '40.107.0.0/16'
152            - '52.100.0.0/14'
153            - '52.238.78.88/32'
154            - '104.47.0.0/17'
155            - '2a01:111:f400::/48'
156            - '2a01:111:f403::/48'
157        DestinationPort: 25
158    filter_main_msrange_sharepoint_1:
159        # SharePoint Online and OneDrive for Business",
160        # "urls": [
161        #       "*.sharepoint.com"
162        # ]
163        DestinationIp|cidr:
164            - '13.107.136.0/22'
165            - '40.108.128.0/17'
166            - '52.104.0.0/14'
167            - '104.146.128.0/17'
168            - '150.171.40.0/22'
169            - '2603:1061:1300::/40'
170            - '2620:1ec:8f8::/46'
171            - '2620:1ec:908::/46'
172            - '2a01:111:f402::/48'
173        DestinationPort:
174            - 80
175            - 443
176        Protocol: 'tcp'
177    filter_main_msrange_office_1:
178        # Microsoft 365 Common and Office Online",
179        # "urls": [
180        #       "*.officeapps.live.com",
181        #       "*.online.office.com",
182        #       "office.live.com"
183        # ],
184        DestinationIp|cidr:
185            - '13.107.6.171/32'
186            - '13.107.18.15/32'
187            - '13.107.140.6/32'
188            - '52.108.0.0/14'
189            - '52.244.37.168/32'
190            - '2603:1006:1400::/40'
191            - '2603:1016:2400::/40'
192            - '2603:1026:2400::/40'
193            - '2603:1036:2400::/40'
194            - '2603:1046:1400::/40'
195            - '2603:1056:1400::/40'
196            - '2603:1063:2000::/38'
197            - '2620:1ec:c::15/128'
198            - '2620:1ec:8fc::6/128'
199            - '2620:1ec:a92::171/128'
200            - '2a01:111:f100:2000::a83e:3019/128'
201            - '2a01:111:f100:2002::8975:2d79/128'
202            - '2a01:111:f100:2002::8975:2da8/128'
203            - '2a01:111:f100:7000::6fdd:6cd5/128'
204            - '2a01:111:f100:a004::bfeb:88cf/128'
205        DestinationPort:
206            - 80
207            - 443
208        Protocol: 'tcp'
209    filter_main_msrange_office_2:
210        # Microsoft 365 Common and Office Online
211        # "urls": [
212        #       "*.auth.microsoft.com",
213        #       "*.msftidentity.com",
214        #       "*.msidentity.com",
215        #       "account.activedirectory.windowsazure.com",
216        #       "accounts.accesscontrol.windows.net",
217        #       "adminwebservice.microsoftonline.com",
218        #       "api.passwordreset.microsoftonline.com",
219        #       "autologon.microsoftazuread-sso.com",
220        #       "becws.microsoftonline.com",
221        #       "ccs.login.microsoftonline.com",
222        #       "clientconfig.microsoftonline-p.net",
223        #       "companymanager.microsoftonline.com",
224        #       "device.login.microsoftonline.com",
225        #       "graph.microsoft.com",
226        #       "graph.windows.net",
227        #       "login-us.microsoftonline.com",
228        #       "login.microsoft.com",
229        #       "login.microsoftonline-p.com",
230        #       "login.microsoftonline.com",
231        #       "login.windows.net",
232        #       "logincert.microsoftonline.com",
233        #       "loginex.microsoftonline.com",
234        #       "nexus.microsoftonline-p.com",
235        #       "passwordreset.microsoftonline.com",
236        #       "provisioningapi.microsoftonline.com"
237        # ]
238        DestinationIp|cidr:
239            - '20.20.32.0/19'
240            - '20.190.128.0/18'
241            - '20.231.128.0/19'
242            - '40.126.0.0/18'
243            - '2603:1006:2000::/48'
244            - '2603:1007:200::/48'
245            - '2603:1016:1400::/48'
246            - '2603:1017::/48'
247            - '2603:1026:3000::/48'
248            - '2603:1027:1::/48'
249            - '2603:1036:3000::/48'
250            - '2603:1037:1::/48'
251            - '2603:1046:2000::/48'
252            - '2603:1047:1::/48'
253            - '2603:1056:2000::/48'
254            - '2603:1057:2::/48'
255        DestinationPort:
256            - 80
257            - 443
258        Protocol: 'tcp'
259    filter_main_msrange_office_3:
260        # Microsoft 365 Common and Office Online
261        #  "urls": [
262        #       "*.compliance.microsoft.com",
263        #       "*.protection.office.com",
264        #       "*.security.microsoft.com",
265        #       "compliance.microsoft.com",
266        #       "defender.microsoft.com",
267        #       "protection.office.com",
268        #       "security.microsoft.com"
269        #  ]
270        DestinationIp|cidr:
271            - '13.107.6.192/32'
272            - '13.107.9.192/32'
273            - '52.108.0.0/14'
274            - '2620:1ec:4::192/128'
275            - '2620:1ec:a92::192/128'
276        DestinationPort: 443
277        Protocol: 'tcp'
278    condition: selection and not 1 of filter_main_*
279falsepositives:
280    - You may have to tune certain domains out that Excel may call out to, such as microsoft or other business use case domains.
281    - Office documents commonly have templates that refer to external addresses, like "sharepoint.ourcompany.com" may have to be tuned.
282    - It is highly recommended to baseline your activity and tune out common business use cases.
283level: medium

References

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