SQL Server started in single mode (command)

Status: experimental
Severity: high
Log source: product windows, category process_creation
Author: mdecrevoisier
Source: github.com/mdecrevoisier/SIGMA-detection-rules

Detects scenarios where an attacker starts SQL Server service in single mode to perform password recovery actions using, for example, the native sqlcmd tool. Indeed, when the SQL Server is started in single user mode, all the users who are a member of the host’s local administrator group can connect to the SQL instance.

MITRE ATT&CK coverage

Tactic	Techniques
Persistence	`T1505.001` Server Software Component: SQL Stored Procedures

Event coverage

Provider	Event	Title
Security-Auditing	Event ID 4688	A new process has been created.

Rule body yaml

title: SQL Server started in single mode (command)
description: Detects scenarios where an attacker starts SQL Server service in single mode to perform password recovery actions using, for example, the native sqlcmd tool. Indeed, when the SQL Server is started in single user mode, all the users who are a member of the host’s local administrator group can connect to the SQL instance.
references:
- https://github.com/mdecrevoisier/EVTX-to-MITRE-Attack/tree/master/TA0003-Persistence/T1505.001-SQL%20Stored%20Procedures
- https://www.sqlshack.com/different-ways-to-start-a-sql-server-single-user-mode/
- https://www.sqlshack.com/recover-lost-sa-password/
tags:
- attack.persistence
- attack.t1505.001
author: mdecrevoisier
status: experimental
logsource:
  product: windows
  category: process_creation
detection: # full command example: "C:\Windows\system32\net.exe" start MSSQL$INSTANCE /m"
  selection:
    EventID: 4688
    NewProcessName|endswith:
      - \net1.exe
      - \net.exe
    CommandLine|contains|all:
      - start
      - MSSQL$
    CommandLine|contains: # indicate single mode
      - /m
      - -m
  condition: selection
falsepositives:
- Master database restore procedure
- Maintenance operation
- Legitim SA account password recovery
level: high

Stages and Predicates

Stage 0: `condition`

selection

Stage 1: `selection`

selection:
  EventID: 4688
  NewProcessName|endswith:
    - \net1.exe
    - \net.exe
  CommandLine|contains|all:
    - start
    - MSSQL$
  CommandLine|contains:
    - /m
    - -m

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

Field	Kind	Values
`CommandLine`	match	`-m` corpus 2 (sigma 2) `/m` `MSSQL$` `start` corpus 13 (sigma 11, splunk 2)
`NewProcessName`	ends_with	`\net.exe` corpus 49 (sigma 49) `\net1.exe` corpus 47 (sigma 47)

`j` / `k`	Scroll down / up
`d` / `u`	Half-page down / up
`gg` / `G`	Top / bottom
`h` / `l`	History back / forward
`f`	Follow link (`Shift` = new tab)
`/`	Focus search
`?`	Toggle this help
`↑` / `↓`	Navigate search results
`Enter`	Open highlighted result
`Esc`	Close results / dialog

`type:`	`events` / `rules` / `providers`
`vendor:`	`sigma` / `elastic` / `splunk` / `kusto` / `chronicle` (vendor name alone also works: `sigma:`, `kql:`, `secops:`…)
`tactic:`	TA-id, slug, or name: `credential_access`, `TA0006`
`technique:`	technique or sub-technique ID: `T1003`, `T1003.001` (alias `tech:`)
`severity:`	`critical` / `high` / `medium` / `low` / `informational` (alias `sev:`)
`risk_score`	Numeric comparison on the Elastic risk score (0 to 100): `risk_score>50`, `risk_score<=20`, `risk_score=99` (alias `risk`; Elastic rules only)
`stages:`	Rules with exactly N pipeline stages
`correlation:`	`single_event` / `sequence` / `alternatives` / `alternatives_cross_log` / `all_required` / `correlated`
`with:`	Co-occurrence event-id; stacks (`with:4624 with:4769`) to require all, while a comma list in one occurrence (`with:4624,4769`) is an either-or group. Implies multi-event
`like:`	Structural neighbors of a rule slug (equivalents + subsumption stricter / broader): `like:comsvcs_lsass_memory_dump-splunk-sysmon`
`groupby:`	Entity-grouping substring match against `group_by_keys`: `groupby:user`, `groupby:host`
`uses:`	Rules whose predicate tree touches the field (any kind, any value): `uses:CommandLine`
`excludes:`	Rules with top-level `not()` clauses on the field (FP whitelists): `excludes:ParentImage`
`field:` / `value:`	Predicate search; narrows rule cards to those with a matching leaf and drives the indicator tier. Unquoted = substring, wildcards allowed (`value:mimikatz`)
`indicator:`	Shorthand for `field:F value:V`: `indicator:Image=*\powershell.exe`
`kind:`	Filter by predicate kind. Narrows rule cards to those carrying a matching predicate leaf (`vendor:elastic kind:cidr_match`) and drives the indicator tier: `contains` / `starts_with` / `ends_with` / `regex` / `cidr` / `eq` / `in` … (operator aliases `op:`/`match:`)
`has:` / `no:`	`sample`, `field`, `notes`, `refs`, `trace`, `thirdparty`, `rule`, `pattern`, `timewindow`, `threshold`, `newterms`, `sigma`/`elastic`/`splunk`/`kusto`/`chronicle`
`-op:val`	Exclude matches; works on most operators but not `type:`/`like:`/`has:`/`no:` (use `no:<flag>` to exclude a rule flag): `tactic:execution -vendor:splunk`. Standalone `-kind:`/`-field:`/`-value:` drop every rule carrying a matching predicate leaf (`type:rules -kind:is_null`)
`field:"…"` / `value:"…"`	Quoted value = anchored exact match (also allows spaces): `value:"net user"`
`a,b`	Comma = OR inside one operator (`vendor:sigma,elastic`, `severity:high,critical`); repeating a facet merges the same way. `field:`/`value:` never split (literal commas)
`vendors:` / `stage:`	Singular and plural spellings fold to the canonical operator and value: `tactics:` = `tactic:`, `type:event` = `type:events`, `correlation:sequences` = `correlation:sequence`, `has:thresholds` = `has:threshold`
`"quoted phrase"`	Exact-match a multi-word phrase (free text)

SQL Server started in single mode (command)

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: `condition`

Stage 1: `selection`

Indicators

Keyboard shortcuts

Search operators

SQL Server started in single mode (command)

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: condition

Stage 1: selection

Indicators

Stage 0: `condition`

Stage 1: `selection`