Suspicious Microsoft 365 Mail Access by ClientAppId

Last updated 9 days ago on 2025-03-26
Created 2 years ago on 2023-07-18

About

Identifies when a Microsoft 365 Mailbox is accessed by a ClientAppId that was observed for the fist time during the last 10 days.
Tags
Domain: CloudData Source: Microsoft 365Use Case: Configuration AuditTactic: Initial AccessLanguage: kuery
Severity
medium
Risk Score
47
MITRE ATT&CK™

Initial Access (TA0001)(opens in a new tab or window)

False Positive Examples
User using a new mail client.
License
Elastic License v2(opens in a new tab or window)

Definition

Rule Type
New Terms Rule
Integration Pack
Prebuilt Security Detection Rules
Index Patterns
filebeat-*logs-o365*
Related Integrations

o365(opens in a new tab or window)

Query
event.dataset:o365.audit and event.provider:Exchange and event.category:web and event.action:MailItemsAccessed and event.outcome:success and 
not o365.audit.ClientAppId : ("13937bba-652e-4c46-b222-3003f4d1ff97" or "6326e366-9d6d-4c70-b22a-34c7ea72d73d" or 
 "a3883eba-fbe9-48bd-9ed3-dca3e0e84250" or "d3590ed6-52b3-4102-aeff-aad2292ab01c" or "27922004-5251-4030-b22d-91ecd9a37ea4" or 
 "1fec8e78-bce4-4aaf-ab1b-5451cc387264" or "26a7ee05-5602-4d76-a7ba-eae8b7b67941" or "00000002-0000-0000-c000-000000000000" or 
 "00000002-0000-0ff1-ce00-000000000000" or "ffcb16e8-f789-467c-8ce9-f826a080d987" or "00000003-0000-0ff1-ce00-000000000000" or 
 "00000004-0000-0ff1-ce00-000000000000" or "00000005-0000-0ff1-ce00-000000000000" or  "00000006-0000-0ff1-ce00-000000000000" or 
 "00000007-0000-0000-c000-000000000000" or "00000007-0000-0ff1-ce00-000000000000" or 
 "00000009-0000-0000-c000-000000000000" or "0000000c-0000-0000-c000-000000000000" or "00000015-0000-0000-c000-000000000000" or 
 "0000001a-0000-0000-c000-000000000000" or "00b41c95-dab0-4487-9791-b9d2c32c80f2" or "022907d3-0f1b-48f7-badc-1ba6abab6d66" or 
 "04b07795-8ddb-461a-bbee-02f9e1bf7b46" or "08e18876-6177-487e-b8b5-cf950c1e598c" or "0cb7b9ec-5336-483b-bc31-b15b5788de71" or 
 "0cd196ee-71bf-4fd6-a57c-b491ffd4fb1e" or "0f698dd4-f011-4d23-a33e-b36416dcb1e6" or "13937bba-652e-4c46-b222-3003f4d1ff97" or 
 "14d82eec-204b-4c2f-b7e8-296a70dab67e" or "16aeb910-ce68-41d1-9ac3-9e1673ac9575" or "1786c5ed-9644-47b2-8aa0-7201292175b6" or 
 "17d5e35f-655b-4fb0-8ae6-86356e9a49f5" or "18fbca16-2224-45f6-85b0-f7bf2b39b3f3" or "1950a258-227b-4e31-a9cf-717495945fc2" or 
 "1b3c667f-cde3-4090-b60b-3d2abd0117f0" or "1fec8e78-bce4-4aaf-ab1b-5451cc387264" or "20a11fe0-faa8-4df5-baf2-f965f8f9972e" or 
 "23523755-3a2b-41ca-9315-f81f3f566a95" or "243c63a3-247d-41c5-9d83-7788c43f1c43" or "268761a2-03f3-40df-8a8b-c3db24145b6b" or 
 "26a7ee05-5602-4d76-a7ba-eae8b7b67941" or "26abc9a8-24f0-4b11-8234-e86ede698878" or "27922004-5251-4030-b22d-91ecd9a37ea4" or 
 "28b567f6-162c-4f54-99a0-6887f387bbcc" or "29d9ed98-a469-4536-ade2-f981bc1d605e" or "2abdc806-e091-4495-9b10-b04d93c3f040" or 
 "2d4d3d8e-2be3-4bef-9f87-7875a61c29de" or "2d7f3606-b07d-41d1-b9d2-0d0c9296a6e8" or "3090ab82-f1c1-4cdf-af2c-5d7a6f3e2cc7" or 
 "35d54a08-36c9-4847-9018-93934c62740c" or "37182072-3c9c-4f6a-a4b3-b3f91cacffce" or "38049638-cc2c-4cde-abe4-4479d721ed44" or 
 "3c896ded-22c5-450f-91f6-3d1ef0848f6e" or "4345a7b9-9a63-4910-a426-35363201d503" or "45a330b1-b1ec-4cc1-9161-9f03992aa49f" or 
 "4765445b-32c6-49b0-83e6-1d93765276ca" or "497effe9-df71-4043-a8bb-14cf78c4b63b" or  "4b233688-031c-404b-9a80-a4f3f2351f90" or 
 "4d5c2d63-cf83-4365-853c-925fd1a64357" or "51be292c-a17e-4f17-9a7e-4b661fb16dd2" or 
 "5572c4c0-d078-44ce-b81c-6cbf8d3ed39e" or "5e3ce6c0-2b1f-4285-8d4b-75ee78787346" or "60c8bde5-3167-4f92-8fdb-059f6176dc0f" or 
 "61109738-7d2b-4a0b-9fe3-660b1ff83505" or "62256cef-54c0-4cb4-bcac-4c67989bdc40" or "6253bca8-faf2-4587-8f2f-b056d80998a7" or 
 "65d91a3d-ab74-42e6-8a2f-0add61688c74" or "66a88757-258c-4c72-893c-3e8bed4d6899" or "67e3df25-268a-4324-a550-0de1c7f97287" or 
 "69893ee3-dd10-4b1c-832d-4870354be3d8" or "74658136-14ec-4630-ad9b-26e160ff0fc6" or "74bcdadc-2fdc-4bb3-8459-76d06952a0e9" or 
 "797f4846-ba00-4fd7-ba43-dac1f8f63013" or "7ab7862c-4c57-491e-8a45-d52a7e023983" or "7ae974c5-1af7-4923-af3a-fb1fd14dcb7e" or 
 "7b7531ad-5926-4f2d-8a1d-38495ad33e17" or "80ccca67-54bd-44ab-8625-4b79c4dc7775" or "835b2a73-6e10-4aa5-a979-21dfda45231c" or 
 "871c010f-5e61-4fb1-83ac-98610a7e9110" or "89bee1f7-5e6e-4d8a-9f3d-ecd601259da7" or "8edd93e1-2103-40b4-bd70-6e34e586362d" or 
 "905fcf26-4eb7-48a0-9ff0-8dcc7194b5ba" or "91ca2ca5-3b3e-41dd-ab65-809fa3dffffa" or "93625bc8-bfe2-437a-97e0-3d0060024faa" or 
 "93d53678-613d-4013-afc1-62e9e444a0a5" or "944f0bd1-117b-4b1c-af26-804ed95e767e" or "94c63fef-13a3-47bc-8074-75af8c65887a" or 
 "95de633a-083e-42f5-b444-a4295d8e9314" or "97cb1f73-50df-47d1-8fb0-0271f2728514" or "98db8bd6-0cc0-4e67-9de5-f187f1cd1b41" or 
 "99b904fd-a1fe-455c-b86c-2f9fb1da7687" or "9ea1ad79-fdb6-4f9a-8bc3-2b70f96e34c7" or "a3475900-ccec-4a69-98f5-a65cd5dc5306" or 
 "a3b79187-70b2-4139-83f9-6016c58cd27b" or "a57aca87-cbc0-4f3c-8b9e-dc095fdc8978" or "a970bac6-63fe-4ec5-8884-8536862c42d4" or 
 "a9b49b65-0a12-430b-9540-c80b3332c127" or "ab9b8c07-8f02-4f72-87fa-80105867a763" or "ae8e128e-080f-4086-b0e3-4c19301ada69" or 
 "b23dd4db-9142-4734-867f-3577f640ad0c" or "b4bddae8-ab25-483e-8670-df09b9f1d0ea" or "b669c6ea-1adf-453f-b8bc-6d526592b419" or 
 "b6e69c34-5f1f-4c34-8cdf-7fea120b8670" or "bb2a2e3a-c5e7-4f0a-88e0-8e01fd3fc1f4" or "bdd48c81-3a58-4ea9-849c-ebea7f6b6360" or 
 "c1c74fed-04c9-4704-80dc-9f79a2e515cb" or "c35cb2ba-f88b-4d15-aa9d-37bd443522e1" or "c44b4083-3bb0-49c1-b47d-974e53cbdf3c" or 
 "c9a559d2-7aab-4f13-a6ed-e7e9c52aec87" or "cc15fd57-2c6c-4117-a88c-83b1d56b4bbe" or "cf36b471-5b44-428c-9ce7-313bf84528de" or 
 "cf53fce8-def6-4aeb-8d30-b158e7b1cf83" or "d176f6e7-38e5-40c9-8a78-3998aab820e7" or "d3590ed6-52b3-4102-aeff-aad2292ab01c" or 
 "d73f4b35-55c9-48c7-8b10-651f6f2acb2e" or "d9b8ec3a-1e4e-4e08-b3c2-5baf00c0fcb0" or "de8bc8b5-d9f9-48b1-a8ad-b748da725064" or 
 "dfe74da8-9279-44ec-8fb2-2aed9e1c73d0" or "e1ef36fd-b883-4dbf-97f0-9ece4b576fc6" or "e64aa8bc-8eb4-40e2-898b-cf261a25954f" or 
 "e9f49c6b-5ce5-44c8-925d-015017e9f7ad" or "ee272b19-4411-433f-8f28-5c13cb6fd407" or "f5eaa862-7f08-448c-9c4e-f4047d4d4521" or 
 "fb78d390-0c51-40cd-8e17-fdbfab77341b" or "fc0f3af4-6835-4174-b806-f7db311fd2f3" or "fdf9885b-dd37-42bf-82e5-c3129ef5a302" or 
 "9199bf20-a13f-4107-85dc-02114787ef48"
)

Install detection rules in Elastic Security

Detect Suspicious Microsoft 365 Mail Access by ClientAppId in the Elastic Security detection engine by installing this rule into your Elastic Stack.

To setup this rule, check out the installation guide for Prebuilt Security Detection Rules(opens in a new tab or window).