Stored business data file deleted by a process that does not own it

Siemphony@siemphonymediumT1565.001unverified

Matches the deletion of a business-record file — a SQL Server data or log file, an Access database or an Outlook store — by any process other than the engine or client that owns it, which is the destructive arm of AN0555 and the only arm that produces a discrete event. The exclusion list is MITRE's AuthorizedProcesses knob populated here with the engines and clients that legitimately remove their own files; anything else unlinking one of these extensions is left to alert. Two limits decide what this can be read as. Backup archives are deliberately not in the extension list: deleting backups to block recovery is T1490, not this technique, and retention jobs pruning .bak files would have dominated the output. And Sysmon has no file-modification event, so the arm the technique is actually named for — a non-owning process writing false values into an existing database file in place — generates no record at all and is structurally invisible here. This rule therefore covers destruction of a record, never falsification of one, and a quiet result says nothing about tampering. File-delete telemetry is also absent from most shipped Sysmon configurations and is expensive to collect, so confirm EventID 23 or 26 is actually being gathered before reading silence as an absence. UNVERIFIED AS AUTHORED — derived from MITRE ATT&CK DET0193, not hand-written and not tested by its author. Any lab result is on this rule's own page.Full description

The 4 SIEM queries below are previews produced by Siemphony’s own translator, not pySigma, and none has been executed against a real backend — review before you deploy.

detection.yml

Sentinel · KQL

Run this as a search.

DeviceFileEvents| where ((FolderPath endswith ".mdf" or FolderPath endswith ".ldf" or FolderPath endswith ".ndf" or FolderPath endswith ".mdb" or FolderPath endswith ".accdb" or FolderPath endswith ".pst" or FolderPath endswith ".ost") and not ((InitiatingProcessFolderPath endswith "\\sqlservr.exe" or InitiatingProcessFolderPath endswith "\\sqlagent.exe" or InitiatingProcessFolderPath endswith "\\sqlwriter.exe" or InitiatingProcessFolderPath endswith "\\mysqld.exe" or InitiatingProcessFolderPath endswith "\\postgres.exe" or InitiatingProcessFolderPath endswith "\\outlook.exe" or InitiatingProcessFolderPath endswith "\\msaccess.exe")))

Splunk · SPL

Run this as a search.

index=* ((TargetFilename="*.mdf" OR TargetFilename="*.ldf" OR TargetFilename="*.ndf" OR TargetFilename="*.mdb" OR TargetFilename="*.accdb" OR TargetFilename="*.pst" OR TargetFilename="*.ost") AND NOT ((Image="*\\sqlservr.exe" OR Image="*\\sqlagent.exe" OR Image="*\\sqlwriter.exe" OR Image="*\\mysqld.exe" OR Image="*\\postgres.exe" OR Image="*\\outlook.exe" OR Image="*\\msaccess.exe")))

Elastic · ES|QL

Run this as a search.

FROM logs-*| WHERE ((TO_LOWER(file.path) LIKE "*.mdf" OR TO_LOWER(file.path) LIKE "*.ldf" OR TO_LOWER(file.path) LIKE "*.ndf" OR TO_LOWER(file.path) LIKE "*.mdb" OR TO_LOWER(file.path) LIKE "*.accdb" OR TO_LOWER(file.path) LIKE "*.pst" OR TO_LOWER(file.path) LIKE "*.ost") AND NOT ((TO_LOWER(process.executable) LIKE "*\\\\sqlservr.exe" OR TO_LOWER(process.executable) LIKE "*\\\\sqlagent.exe" OR TO_LOWER(process.executable) LIKE "*\\\\sqlwriter.exe" OR TO_LOWER(process.executable) LIKE "*\\\\mysqld.exe" OR TO_LOWER(process.executable) LIKE "*\\\\postgres.exe" OR TO_LOWER(process.executable) LIKE "*\\\\outlook.exe" OR TO_LOWER(process.executable) LIKE "*\\\\msaccess.exe")))

Wazuh · XML rule

Deploy to your manager — this is a rule, not a search.

<group name="sigma,windows,file_delete,">  <!-- Rule ids must be unique on your manager; 100000+ is the user range. -->  <rule id="100000" level="7">    <!-- Set <if_sid> to the decoder/base rule for windows so this only evaluates relevant events. -->    <field name="TargetFilename" type="pcre2">(?i)(\.mdf$|\.ldf$|\.ndf$|\.mdb$|\.accdb$|\.pst$|\.ost$)</field>    <field name="Image" negate="yes" type="pcre2">(?i)(\\sqlservr\.exe$|\\sqlagent\.exe$|\\sqlwriter\.exe$|\\mysqld\.exe$|\\postgres\.exe$|\\outlook\.exe$|\\msaccess\.exe$)</field>    <description>Stored business data file deleted by a process that does not own it</description>    <mitre>      <id>T1565.001</id>    </mitre>  </rule></group>

At a glance

Logsource: file_delete / windows
Level: medium
Category: impact_destruction
Sigma status: experimental
Backends: 4 of 4 rendered
Updated: 30 Aug 2026
Rule ID: 95361a8a-b91f-43e3-a3ef-f1eafc6f5a1b

ATT&CKT1565.001

T1565.001Stored Data Manipulation

ATT&CK® is a registered trademark of The MITRE Corporation. These mappings are the rule author’s, and are neither reviewed nor endorsed by MITRE.

Lessonimpact destruction

impact destruction

01 · What this rule detects

The work an operator does to make recovery impossible before, or while, destroying data — deleting volume shadow copies, wiping backup catalogs, disabling Windows recovery and boot repair, and deleting or overwriting files recursively. Most of it happens in a short burst immediately before encryption, which is why the precursors are the part worth detecting: by the time file modification volume is the signal, the decision has already been made for you. This overlaps deliberately with log clearing — the same burst usually destroys evidence and recovery together — but keep the two rules apart, because they point at different questions.

02 · Telemetry you need

Process creation with full command lines — Sysmon EventID 1, or Security 4688 with Audit Process Creation and the command-line inclusion policy; without the second policy you see that vssadmin ran and nothing about what it did
The utilities themselves: vssadmin, wmic shadowcopy, wbadmin, bcdedit, cipher, and the PowerShell and WMI equivalents that never touch a command-line binary
Sysmon EventID 23 and 26 (FileDelete and FileDeleteDetected) — not in the default configuration, and the archiving variant needs disk space budgeted for it
Service and provider activity for the Volume Shadow Copy service, and the backup product's own logs, which record deletion the operating system does not
Security 4663 for delete access on protected shares — Audit Object Access plus a SACL, off by default and inert without the SACL

03 · How the logic works

These command lines are short, fixed and close to unique, which makes this one of the few categories where string matching against the command line is the right primary approach rather than a fallback. Structure each as image AND destructive verb: matching vssadmin alone catches every backup product listing shadows, whereas vssadmin with delete does not. Allow for argument reordering, abbreviation and the several spellings of the same operation, and remember that the same effect is reachable through WMI and the COM interfaces without running the utility at all — so a rule set that names only the executables has a hole in it that any competent tooling walks through. The mass-encryption half is a rate problem: file modifications per process per minute, which Sigma cannot express and which belongs in the correlation layer.

04 · Common false positives

Backup software managing its own shadow storage and pruning old copies — Veeam, Acronis, Windows Server Backup and the built-in scheduled tasks
Disk cleanup and storage reclamation removing shadow copies when a volume fills
Imaging, provisioning and task sequences that use bcdedit and reset recovery configuration by design
Non-persistent VDI and lab rebuild workflows that discard machine state on every cycle
Developers and build systems recursively deleting output directories

05 · Detection maturity

Tier 1 — starting point: Matches vssadmin and wbadmin deletion command lines.
Tier 2 — tuned: Covers the WMI and PowerShell routes and boot configuration tampering, with backup hosts and maintenance windows excluded.
Tier 3 — correlated: Correlates recovery destruction with log clearing, service stops and file modification rate from the same host and process tree.

Tuning & false positivesexperimental · 4 declared

experimental (current stage)
test
stable

Written and reasoned about, but not yet run against real telemetry. Expect to tune it before trusting it.

Tuning tips

This should be a near-silent category. If it is noisy, find out what is deleting recovery points routinely and fix that rather than filtering it
Never exclude by account — the accounts used here are administrative by definition, which is the point
Scope exclusions to the specific backup hosts and their maintenance windows, and revisit them when the backup product changes
Alert on failed attempts as well as successful ones; a denied shadow deletion is the same intent and better news
Escalate hard on the combination — shadow deletion, log clearing and service stops from one host inside a few minutes is a different alert from any of them alone

Declared by the author

Database maintenance done by hand. A DBA detaching a database and deleting its .mdf and .ldf from Explorer, cmd.exe or PowerShell, or a developer resetting a local instance, matches precisely because the deleting image is a shell rather than the engine, and on a shared development server this is the most frequent source.
Antivirus and EDR engines removing a file. A scheduled scan quarantining an infected .pst or .ost attachment store, or deleting a corrupted Access or SQL data file, deletes it under the scanner's own image, which is a non-owning process exactly like an attacker's shell.
Mailbox cache and profile churn driven by something other than outlook.exe — profile migration tooling, a mail-archiving product clearing a stale .ost, or a user deleting an old .pst archive from Explorer.
Installers and uninstallers. msiexec.exe and vendor setup programs remove bundled Access .mdb files and SQL Express data files during an upgrade, a repair run or a clean removal.

Noise checknot tested

No baseline event covers this rule’s log type (file_delete / windows), so the rule was never evaluated. This is missing data, not a clean result — nothing was checked either way.

Run live against 65 hand-written events of ordinary corporate activity — backup agents, software distribution, patching, helpdesk scripts, EDR. It says nothing about how often the rule would fire in production, which is the number that actually exhausts an analyst.

Verificationnone

Never run

The lab has not evaluated this composition. A run needs a dataset of its log type — a capture of the technique it claims, or the benign baseline — and not every rule has one. Some are also held back by the evaluator’s own safety limits.

Other compositions here have been run and some carry the badge — this one has not, so nothing about it has been shown either way. Read the rule and its noise check on their own terms; silence here is the absence of evidence, not evidence of a problem.

Test it yourselfin your browser

Runs here in your browser against public attack recordings. A preview — not the verification badge.

Recordings of T1565.001, evaluated against their file_delete events.

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Stored business data file deleted by a process that does not own it

The detection

detection.yml

Sentinel · KQL

Splunk · SPL

Elastic · ES|QL

Wazuh · XML rule

Community

Verdicts from engineers who deployed it