Potential Tampering With RDP Related Registry Keys Via Reg.EXE

Status: test
Severity: high
Log source: product windows, category process_creation
Author: pH-T (Nextron Systems), @Kostastsale, TheDFIRReport
Source: github.com/SigmaHQ/sigma

Detects the execution of "reg.exe" for enabling/disabling the RDP service on the host by tampering with the 'CurrentControlSet\Control\Terminal Server' values

MITRE ATT&CK coverage

Tactic	Techniques
Persistence	`T1112` Modify Registry
Defense Impairment	`T1112` Modify Registry
Lateral Movement	`T1021.001` Remote Services: Remote Desktop Protocol

Event coverage

Provider	Event	Title
Sysmon	Event ID 1	Process creation

Rule body yaml

title: Potential Tampering With RDP Related Registry Keys Via Reg.EXE
id: 0d5675be-bc88-4172-86d3-1e96a4476536
status: test
description: Detects the execution of "reg.exe" for enabling/disabling the RDP service on the host by tampering with the 'CurrentControlSet\Control\Terminal Server' values
references:
    - https://thedfirreport.com/2022/02/21/qbot-and-zerologon-lead-to-full-domain-compromise/
    - http://etutorials.org/Microsoft+Products/microsoft+windows+server+2003+terminal+services/Chapter+6+Registry/Registry+Keys+for+Terminal+Services/ # Contain description for most of the keys mentioned here (check it out if you want more information
    - http://woshub.com/rds-shadow-how-to-connect-to-a-user-session-in-windows-server-2012-r2/ # Related to the Shadow RPD technique
    - https://admx.help/HKLM/SOFTWARE/Policies/Microsoft/Windows%20NT/Terminal%20Services # Contain description for most of the keys mentioned here (check it out if you want more information)
    - https://bazaar.abuse.ch/sample/6f3aa9362d72e806490a8abce245331030d1ab5ac77e400dd475748236a6cc81/
    - https://blog.sekoia.io/darkgate-internals/
    - https://blog.talosintelligence.com/understanding-the-phobos-affiliate-structure/
    - https://github.com/redcanaryco/atomic-red-team/blob/02c7d02fe1f1feb0fc7944550408ea8224273994/atomics/T1112/T1112.md#atomic-test-63---disable-remote-desktop-anti-alias-setting-through-registry
    - https://github.com/redcanaryco/atomic-red-team/blob/02c7d02fe1f1feb0fc7944550408ea8224273994/atomics/T1112/T1112.md#atomic-test-64---disable-remote-desktop-security-settings-through-registry
    - https://github.com/redcanaryco/atomic-red-team/blob/dd526047b8c399c312fee47d1e6fb531164da54d/atomics/T1112/T1112.yaml#L790
    - https://learn.microsoft.com/en-us/windows-hardware/customize/desktop/unattend/microsoft-windows-terminalservices-rdp-winstationextensions-securitylayer
    - https://threathunterplaybook.com/hunts/windows/190407-RegModEnableRDPConnections/notebook.html
    - https://twitter.com/SagieSec/status/1469001618863624194?t=HRf0eA0W1YYzkTSHb-Ky1A&s=03 # Related to the Shadow RPD technique
    - https://web.archive.org/web/20200929062532/https://blog.menasec.net/2019/02/threat-hunting-rdp-hijacking-via.html # Related to RDP hijacking via the "ServiceDll" key
    - https://www.trendmicro.com/en_us/research/25/i/unmasking-the-gentlemen-ransomware.html
author: pH-T (Nextron Systems), @Kostastsale, TheDFIRReport
date: 2022-02-12
modified: 2025-11-22
tags:
    - attack.persistence
    - attack.lateral-movement
    - attack.defense-impairment
    - attack.t1021.001
    - attack.t1112
logsource:
    product: windows
    category: process_creation
detection:
    selection_main_img:
        - Image|endswith: '\reg.exe'
        - OriginalFileName: 'reg.exe'
    selection_main_cli:
        CommandLine|contains|all:
            - ' add '
            - '\CurrentControlSet\Control\Terminal Server'
            - 'REG_DWORD'
            - ' /f'
    selection_values_1:
        CommandLine|contains|all:
            - 'Licensing Core'
            - 'EnableConcurrentSessions'
    selection_values_2:
        CommandLine|contains:
            - 'AllowTSConnections'
            - 'fDenyTSConnections'
            - 'fEnableWinStation'
            - 'fSingleSessionPerUser'
            - 'IdleWinStationPoolCount'
            - 'MaxInstanceCount'
            - 'SecurityLayer'
            - 'TSAdvertise'
            - 'TSAppCompat'
            - 'TSEnabled'
            - 'TSUserEnabled'
            - 'WinStations\RDP-Tcp'
    filter_main_values_tls:
        CommandLine|contains|all:
            - 'SecurityLayer'
            - '02'  # TLS Enabled
    condition: all of selection_main_* and 1 of selection_values_* and not 1 of filter_main_*
falsepositives:
    - Unknown
level: high

Stages and Predicates

Stage 0: `condition`

all of selection_main_* and 1 of selection_values_* and not 1 of filter_main_*

Stage 1: `selection_main_img`

selection_main_img:
    - Image|endswith: '\reg.exe'
    - OriginalFileName: 'reg.exe'

Stage 2: `selection_main_cli`

selection_main_cli:
    CommandLine|contains|all:
        - ' add '
        - '\CurrentControlSet\Control\Terminal Server'
        - 'REG_DWORD'
        - ' /f'

Stage 3: `selection_values_1`

selection_values_1:
    CommandLine|contains|all:
        - 'Licensing Core'
        - 'EnableConcurrentSessions'

Stage 4: `selection_values_2`

selection_values_2:
    CommandLine|contains:
        - 'AllowTSConnections'
        - 'fDenyTSConnections'
        - 'fEnableWinStation'
        - 'fSingleSessionPerUser'
        - 'IdleWinStationPoolCount'
        - 'MaxInstanceCount'
        - 'SecurityLayer'
        - 'TSAdvertise'
        - 'TSAppCompat'
        - 'TSEnabled'
        - 'TSUserEnabled'
        - 'WinStations\RDP-Tcp'

Stage 5: `not filter_main_values_tls`

filter_main_values_tls:
    CommandLine|contains|all:
        - 'SecurityLayer'
        - '02'

Exclusions

Top-level NOT(...) conjuncts: predicates this rule actively suppresses.

Field	Kind	Excluded values
`CommandLine`	match	`02`
`CommandLine`	match	`SecurityLayer`

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	`/f` corpus 3 (sigma 2, chronicle 1) `add` corpus 14 (sigma 12, splunk 1, chronicle 1) `AllowTSConnections` corpus 2 (sigma 1, chronicle 1) `EnableConcurrentSessions` corpus 2 (sigma 1, chronicle 1) `IdleWinStationPoolCount` corpus 2 (sigma 1, chronicle 1) `Licensing Core` corpus 2 (sigma 1, chronicle 1) `MaxInstanceCount` corpus 2 (sigma 1, chronicle 1) `REG_DWORD` corpus 3 (sigma 1, chronicle 1, kusto 1) `SecurityLayer` `TSAdvertise` corpus 2 (sigma 1, chronicle 1) `TSAppCompat` `TSEnabled` corpus 2 (sigma 1, chronicle 1) `TSUserEnabled` corpus 2 (sigma 1, chronicle 1) `WinStations\RDP-Tcp` `\CurrentControlSet\Control\Terminal Server` `fDenyTSConnections` corpus 2 (sigma 1, chronicle 1) `fEnableWinStation` corpus 2 (sigma 1, chronicle 1) `fSingleSessionPerUser` corpus 2 (sigma 1, chronicle 1)
`Image`	ends_with	`\reg.exe` corpus 58 (sigma 58)
`OriginalFileName`	eq	`reg.exe` corpus 42 (sigma 32, splunk 8, elastic 2)

`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)

Potential Tampering With RDP Related Registry Keys Via Reg.EXE

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: `condition`

Stage 1: `selection_main_img`

Stage 2: `selection_main_cli`

Stage 3: `selection_values_1`

Stage 4: `selection_values_2`

Stage 5: `not filter_main_values_tls`

Exclusions

Indicators

Keyboard shortcuts

Search operators

Potential Tampering With RDP Related Registry Keys Via Reg.EXE

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: condition

Stage 1: selection_main_img

Stage 2: selection_main_cli

Stage 3: selection_values_1

Stage 4: selection_values_2

Stage 5: not filter_main_values_tls

Exclusions

Indicators

Stage 0: `condition`

Stage 1: `selection_main_img`

Stage 2: `selection_main_cli`

Stage 3: `selection_values_1`

Stage 4: `selection_values_2`

Stage 5: `not filter_main_values_tls`