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Rule 92214 creates maximum-level false-positive alerts when opening office files #20317

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PiRomant opened this issue Nov 17, 2023 · 1 comment · May be fixed by #23016
Open

Rule 92214 creates maximum-level false-positive alerts when opening office files #20317

PiRomant opened this issue Nov 17, 2023 · 1 comment · May be fixed by #23016

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@PiRomant
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PiRomant commented Nov 17, 2023 •
edited

Wazuh version Component Action type
4.6.0 Rules false-positive

Description

Rule 92214 creates maximum-level false-positive alerts when opening office files. A new LNK file appears with every open office file.
Just open %appdata%\Microsoft\Office\Recent and you will see several LNKs.

Current results

Rules triggering with opening every new office file.

wazuh/ruleset/rules/0830-sysmon_id_11.xml

Lines 158 to 163 in dff3ece

<rule id="92214" level="15">
<if_group>sysmon_event_11</if_group>
<field name="win.eventdata.image" type="pcre2">(?i)(winword|excel|powerpnt|outlook)\.exe</field>
<field name="win.eventdata.targetFilename" type="pcre2">(?i)appdata\\\\.+\.lnk</field>
<options>no_full_log</options>
<description>Suspicious file created by Microsoft Office process: $(win.eventdata.image) created $(win.eventdata.targetFilename)</description>

ex: C:\\Users\\user\\AppData\\Roaming\\Microsoft\\Office\\Recent\\Document.docx.LNK

Expected results

LNK files should be ignored in the Recent.

Resources

Log reference

https://answers.microsoft.com/en-us/msoffice/forum/all/how-to-disable-from-logging-all-recent-files-in/f229f69b-d46f-4fa4-9d24-072164032cd6
#13631
@vzderic
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vzderic commented Apr 19, 2024

Quick fix
Create custom_rules.xml and add following lines:

sysmon_event_11 (?i)(winword|excel|powerpnt|outlook)\.exe (?i)appdata\\\\(?!Roaming\\\\Microsoft\\\\).+\.lnk no_full_log Suspicious file created by Microsoft Office process: $(win.eventdata.image) created $(win.eventdata.targetFilename) T1027

@PiRomant PiRomant linked a pull request Apr 20, 2024 that will close this issue
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Fix rule 92214 PiRomant/wazuh
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@vzderic @PiRomant