Office Application Initiated Network Connection To Non-Local IP

title: Office Application Initiated Network Connection To Non-Local IP
id: 75e33ce3-ae32-4dcc-9aa8-a2a3029d6f84
status: test
description: |
    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.
references:
    - https://corelight.com/blog/detecting-cve-2021-42292
    - https://learn.microsoft.com/de-de/microsoft-365/enterprise/urls-and-ip-address-ranges?view=o365-worldwide
author: Christopher Peacock '@securepeacock', SCYTHE '@scythe_io', Florian Roth (Nextron Systems), Tim Shelton, Nasreddine Bencherchali (Nextron Systems)
date: 2021-11-10
modified: 2025-10-17
tags:
    - attack.execution
    - attack.t1203
logsource:
    category: network_connection
    product: windows
detection:
    selection:
        Image|endswith:
            - '\excel.exe'
            - '\outlook.exe'
            - '\powerpnt.exe'
            - '\winword.exe'
            - '\wordview.exe'
        Initiated: 'true'
    filter_main_local_ranges:
        DestinationIp|cidr:
            - '127.0.0.0/8'
            - '10.0.0.0/8'
            - '172.16.0.0/12'
            - '192.168.0.0/16'
            - '169.254.0.0/16'
            - '::1/128'  # IPv6 loopback
            - 'fe80::/10'  # IPv6 link-local addresses
            - 'fc00::/7'  # IPv6 private addresses
    filter_main_msrange_generic:
        DestinationIp|cidr:
            - '2.16.56.0/23' # Akamai International B.V.
            - '2.17.248.0/21' # Akamai International B.V.
            - '13.107.240.0/21' # Microsoft Corporation
            - '20.184.0.0/13' # Microsoft Corporation
            - '23.61.224.0/20' # Akamai-AS
            - '20.192.0.0/10' # Microsoft Corporation
            - '23.72.0.0/13' # Akamai International B.V.
            - '23.3.88.0/22' # Akamai-AS
            - '23.216.132.0/22' # Akamai-AS
            - '40.76.0.0/14' # Microsoft Corporation
            - '51.10.0.0/15' # Microsoft Corporation
            - '51.103.0.0/16' # Microsoft Corporation
            - '51.104.0.0/15' # Microsoft Corporation
            - '51.142.136.0/22' # Microsoft Corporation - https://ipinfo.io/AS8075/51.140.0.0/14-51.142.136.0/22
            - '52.160.0.0/11' # Microsoft Corporation - https://ipinfo.io/AS8075/52.160.0.0/11
            - '95.101.96.0/21' # Akamai-As
            - '204.79.197.0/24' # Microsoft Corporation
    filter_main_msrange_exchange_1:
        # Exchange Online
        # "urls": [
        #       "outlook.cloud.microsoft",
        #       "outlook.office.com",
        #       "outlook.office365.com"
        # ]
        DestinationIp|cidr:
            - '13.107.4.0/22'
            - '13.107.6.152/31'
            - '13.107.18.10/31'
            - '13.107.42.0/23'
            - '13.107.128.0/22'
            - '23.35.224.0/20'
            - '23.53.40.0/22'
            - '23.103.160.0/20'
            - '23.216.76.0/22'
            - '40.96.0.0/13'
            - '40.104.0.0/15'
            - '52.96.0.0/14'
            - '131.253.33.215/32'
            - '132.245.0.0/16'
            - '150.171.32.0/22'
            - '204.79.197.215/32'
            - '2603:1006::/40'
            - '2603:1016::/36'
            - '2603:1026::/36'
            - '2603:1036::/36'
            - '2603:1046::/36'
            - '2603:1056::/36'
            - '2620:1ec:4::152/128'
            - '2620:1ec:4::153/128'
            - '2620:1ec:c::10/128'
            - '2620:1ec:c::11/128'
            - '2620:1ec:d::10/128'
            - '2620:1ec:d::11/128'
            - '2620:1ec:8f0::/46'
            - '2620:1ec:900::/46'
            - '2620:1ec:a92::152/128'
            - '2620:1ec:a92::153/128'
        DestinationPort:
            - 80
            - 443
    filter_main_msrange_exchange_2:
        # Exchange Online
        # "urls": [
        #       "outlook.office365.com",
        #       "smtp.office365.com"
        # ]
        DestinationIp|cidr:
            - '13.107.6.152/31'
            - '13.107.18.10/31'
            - '13.107.128.0/22'
            - '23.103.160.0/20'
            - '40.96.0.0/13'
            - '40.104.0.0/15'
            - '52.96.0.0/14'
            - '131.253.33.215/32'
            - '132.245.0.0/16'
            - '150.171.32.0/22'
            - '204.79.197.215/32'
            - '2603:1006::/40'
            - '2603:1016::/36'
            - '2603:1026::/36'
            - '2603:1036::/36'
            - '2603:1046::/36'
            - '2603:1056::/36'
            - '2620:1ec:4::152/128'
            - '2620:1ec:4::153/128'
            - '2620:1ec:c::10/128'
            - '2620:1ec:c::11/128'
            - '2620:1ec:d::10/128'
            - '2620:1ec:d::11/128'
            - '2620:1ec:8f0::/46'
            - '2620:1ec:900::/46'
            - '2620:1ec:a92::152/128'
            - '2620:1ec:a92::153/128'
        DestinationPort:
            - 143
            - 587
            - 993
            - 995
        Protocol: 'tcp'
    filter_main_msrange_exchange_3:
        # Exchange Online
        # "urls": [
        #       "*.protection.outlook.com"
        #  ]
        DestinationIp|cidr:
            - '40.92.0.0/15'
            - '40.107.0.0/16'
            - '52.100.0.0/14'
            - '52.238.78.88/32'
            - '104.47.0.0/17'
            - '2a01:111:f400::/48'
            - '2a01:111:f403::/48'
        DestinationPort: 443
    filter_main_msrange_exchange_4:
        # Exchange Online
        # "urls": [
        #       "*.mail.protection.outlook.com",
        #       "*.mx.microsoft"
        #  ]
        DestinationIp|cidr:
            - '40.92.0.0/15'
            - '40.107.0.0/16'
            - '52.100.0.0/14'
            - '52.238.78.88/32'
            - '104.47.0.0/17'
            - '2a01:111:f400::/48'
            - '2a01:111:f403::/48'
        DestinationPort: 25
    filter_main_msrange_sharepoint_1:
        # SharePoint Online and OneDrive for Business",
        # "urls": [
        #       "*.sharepoint.com"
        # ]
        DestinationIp|cidr:
            - '13.107.136.0/22'
            - '40.108.128.0/17'
            - '52.104.0.0/14'
            - '104.146.128.0/17'
            - '150.171.40.0/22'
            - '2603:1061:1300::/40'
            - '2620:1ec:8f8::/46'
            - '2620:1ec:908::/46'
            - '2a01:111:f402::/48'
        DestinationPort:
            - 80
            - 443
        Protocol: 'tcp'
    filter_main_msrange_office_1:
        # Microsoft 365 Common and Office Online",
        # "urls": [
        #       "*.officeapps.live.com",
        #       "*.online.office.com",
        #       "office.live.com",
        #       "office.com.akadns.net"
        # ],
        DestinationIp|cidr:
            - '13.107.6.171/32'
            - '13.107.18.15/32'
            - '13.107.140.6/32'
            - '20.64.0.0/10'
            - '52.108.0.0/14'
            - '52.244.37.168/32'
            - '2603:1006:1400::/40'
            - '2603:1016:2400::/40'
            - '2603:1026:2400::/40'
            - '2603:1036:2400::/40'
            - '2603:1046:1400::/40'
            - '2603:1056:1400::/40'
            - '2603:1063:2000::/38'
            - '2620:1ec:c::15/128'
            - '2620:1ec:8fc::6/128'
            - '2620:1ec:a92::171/128'
            - '2a01:111:f100:2000::a83e:3019/128'
            - '2a01:111:f100:2002::8975:2d79/128'
            - '2a01:111:f100:2002::8975:2da8/128'
            - '2a01:111:f100:7000::6fdd:6cd5/128'
            - '2a01:111:f100:a004::bfeb:88cf/128'
        DestinationPort:
            - 80
            - 443
        Protocol: 'tcp'
    filter_main_msrange_office_2:
        # Microsoft 365 Common and Office Online
        # "urls": [
        #       "*.auth.microsoft.com",
        #       "*.msftidentity.com",
        #       "*.msidentity.com",
        #       "account.activedirectory.windowsazure.com",
        #       "accounts.accesscontrol.windows.net",
        #       "adminwebservice.microsoftonline.com",
        #       "api.passwordreset.microsoftonline.com",
        #       "autologon.microsoftazuread-sso.com",
        #       "becws.microsoftonline.com",
        #       "ccs.login.microsoftonline.com",
        #       "clientconfig.microsoftonline-p.net",
        #       "cloudapp.azure.com",
        #       "companymanager.microsoftonline.com",
        #       "device.login.microsoftonline.com",
        #       "graph.microsoft.com",
        #       "graph.windows.net",
        #       "login-us.microsoftonline.com",
        #       "login.microsoft.com",
        #       "login.microsoftonline-p.com",
        #       "login.microsoftonline.com",
        #       "login.windows.net",
        #       "logincert.microsoftonline.com",
        #       "loginex.microsoftonline.com",
        #       "nexus.microsoftonline-p.com",
        #       "passwordreset.microsoftonline.com",
        #       "provisioningapi.microsoftonline.com",
        #       "web.core.windows.net",
        # ]
        DestinationIp|cidr:
            - '172.128.0.0/10'
            - '20.20.32.0/19'
            - '20.103.156.88/32' # msn.com
            - '20.190.128.0/18'
            - '20.231.128.0/19'
            - '40.126.0.0/18'
            - '57.150.0.0/15'
            - '2603:1006:2000::/48'
            - '2603:1007:200::/48'
            - '2603:1016:1400::/48'
            - '2603:1017::/48'
            - '2603:1026:3000::/48'
            - '2603:1027:1::/48'
            - '2603:1036:3000::/48'
            - '2603:1037:1::/48'
            - '2603:1046:2000::/48'
            - '2603:1047:1::/48'
            - '2603:1056:2000::/48'
            - '2603:1057:2::/48'
        DestinationPort:
            - 80
            - 443
        Protocol: 'tcp'
    filter_main_msrange_office_3:
        # Microsoft 365 Common and Office Online
        #  "urls": [
        #       "*.compliance.microsoft.com",
        #       "*.data.microsoft.com",
        #       "*.protection.office.com",
        #       "*.security.microsoft.com",
        #       "compliance.microsoft.com",
        #       "defender.microsoft.com",
        #       "protection.office.com",
        #       "security.microsoft.com",
        #       "teams.microsoft.com",
        #  ]
        DestinationIp|cidr:
            - '13.64.0.0/11'
            - '13.107.6.192/32'
            - '13.107.9.192/32'
            - '13.89.179.14/32'
            - '20.40.0.0/14'
            - '20.48.0.0/12'
            - '20.64.0.0/12'
            - '52.123.0.0/16'
            - '52.108.0.0/14'
            - '52.136.0.0/13'
            - '57.150.0.0/15'
            - '80.239.150.67/32' # Arelion Sweden AB
            - '2620:1ec:4::192/128'
            - '2620:1ec:a92::192/128'
        DestinationPort: 443
        Protocol: 'tcp'
    filter_main_destination_host:
        DestinationHostname|endswith: '.deploy.static.akamaitechnologies.com'
        DestinationPort: 443
        Protocol: 'tcp'
    condition: selection and not 1 of filter_main_*
falsepositives:
    - You may have to tune certain domains out that Excel may call out to, such as microsoft or other business use case domains.
    - Office documents commonly have templates that refer to external addresses, like "sharepoint.ourcompany.com" may have to be tuned.
    - It is highly recommended to baseline your activity and tune out common business use cases.
level: medium