Rouge RDP: Suspicious File Creation

Author: Cyb3rMonk
Source: github.com/Cyb3r-Monk/Threat-Hunting-and-Detection

Below query detects file creations of mstsc.exe where it also makes a network connection to a public IP address. This behavior is an indication of Rogue RDP.
False Positives: Copying files to the local machine over RDP may cause false positives.

MITRE ATT&CK coverage

Tactic	Techniques
Persistence	`T1556` Modify Authentication Process
Defense Impairment	`T1556` Modify Authentication Process
Credential Access	`T1556` Modify Authentication Process

References

Event coverage

Provider	Event/ActionType	Title
Sysmon	Event ID 3	Network connection
Security-Auditing	Event ID 5156	The Windows Filtering Platform has permitted a connection.
Defender-DeviceNetworkEvents	ConnectionSuccess	Connection succeeded

Rule body kusto

// Author: Cyb3rMonk(https://twitter.com/Cyb3rMonk, https://mergene.medium.com)
// Description: Detect file creations of mstsc.exe where it also makes a network connection to a public IP address. This behavior is an indication of Rogue RDP. 
//
// Query parameters:
// there might be more file types that can be leveraged
// adjust file types to monitor
// consider DLL sideloading opportunities if you want to filter based on folders.
let file_types = dynamic([".dll", ".exe", ".cpl", ".pif", ".com", ".js", ".vbs", ".wsh", ".vbe", ".jse", ".bat", ".cmd", ".lnk", ".url", ".png", ".hta", ".svg"]);
let _query_period = 7d;
DeviceNetworkEvents
| where Timestamp > ago(_query_period)
| where ActionType in ("ConnectionSuccess")
| where InitiatingProcessFileName =~ "mstsc.exe"
| where RemoteIPType == "Public"
| project Timestamp, DeviceId, DeviceName, InitiatingProcessFileName=tolower(InitiatingProcessFileName), InitiatingProcessId, RemoteIP, RemoteUrl, RemotePort, NetworkTimestamp = Timestamp
| join kind=inner (
    DeviceFileEvents
    | where Timestamp > ago(_query_period)
    | where ActionType in ("FileCreated", "FileModified")
    | where InitiatingProcessFileName =~ "mstsc.exe" 
    | where FileName has_any (file_types)
    | extend InitiatingProcessFileName=tolower(InitiatingProcessFileName), FileTimestamp = Timestamp
    ) on InitiatingProcessFileName, DeviceId // InitiatingProcessId or InitiatingProcessUniqueId can be used as well but be mindful of multiple connections and telemetry sampling.
    // adjust time between RDP connection and file creation
    | where datetime_diff('minute', FileTimestamp, NetworkTimestamp) < 60

Stages and Predicates

Parameters

let file_types = dynamic([".dll", ".exe", ".cpl", ".pif", ".com", ".js", ".vbs", ".wsh", ".vbe", ".jse", ".bat", ".cmd", ".lnk", ".url", ".png", ".hta", ".svg"]);
let _query_period = 7d;

Stage 1: `source`

DeviceNetworkEvents

Stage 2: `where`

| where Timestamp > ago(_query_period)

Stage 3: `where`

| where ActionType in ("ConnectionSuccess")

Stage 4: `where`

| where InitiatingProcessFileName =~ "mstsc.exe"

Stage 5: `where`

| where RemoteIPType == "Public"

Stage 6: `project`

| project Timestamp, DeviceId, DeviceName, InitiatingProcessFileName=tolower(InitiatingProcessFileName), InitiatingProcessId, RemoteIP, RemoteUrl, RemotePort, NetworkTimestamp = Timestamp

Stage 7: `join`

| join kind=inner (
    DeviceFileEvents
    | where Timestamp > ago(_query_period)
    | where ActionType in ("FileCreated", "FileModified")
    | where InitiatingProcessFileName =~ "mstsc.exe" 
    | where FileName has_any (file_types)
    | extend InitiatingProcessFileName=tolower(InitiatingProcessFileName), FileTimestamp = Timestamp
    ) on InitiatingProcessFileName, DeviceId

Stage 8: `where` where FileTimestamp - NetworkTimestamp < 1h

| where datetime_diff('minute', FileTimestamp, NetworkTimestamp) < 60

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
`ActionType`	in	`ConnectionSuccess` transforms: `cased` corpus 9 (kusto 9) `FileCreated` transforms: `cased` corpus 8 (kusto 8) `FileModified` transforms: `cased`
`FileName`	match	`.bat` corpus 2 (kusto 2) `.cmd` corpus 2 (kusto 2) `.com` corpus 2 (kusto 2) `.cpl` corpus 2 (kusto 2) `.dll` corpus 2 (kusto 2) `.exe` corpus 2 (kusto 2) `.hta` `.js` `.jse` `.lnk` `.pif` `.png` `.svg` `.url` `.vbe` `.vbs` corpus 2 (kusto 2) `.wsh`
`InitiatingProcessFileName`	eq	`mstsc.exe`
`RemoteIPType`	eq	`Public` transforms: `cased` corpus 5 (kusto 5)

Output fields

Fields the rule emits when it matches. Chronicle authors list these in the outcome block; they appear on the detection and $risk_score drives alerting. Sentinel / Defender XDR rules build them up through project / summarize / extend stages. Sentinel maps these into alert fields via entityMappings and customDetails; Defender XDR custom detections surface them as alert fields directly.

Field	Source
`DeviceId`	`project`
`DeviceName`	`project`
`InitiatingProcessFileName`	`project`
`InitiatingProcessId`	`project`
`NetworkTimestamp`	`project`
`RemoteIP`	`project`
`RemotePort`	`project`
`RemoteUrl`	`project`
`Timestamp`	`project`

`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)

Rouge RDP: Suspicious File Creation

MITRE ATT&CK coverage

References

Event coverage

Rule body kusto

Stages and Predicates

Parameters

Stage 1: `source`

Stage 2: `where`

Stage 3: `where`

Stage 4: `where`

Stage 5: `where`

Stage 6: `project`

Stage 7: `join`

Stage 8: `where` where FileTimestamp - NetworkTimestamp < 1h

Indicators

Output fields

Keyboard shortcuts

Search operators

Rouge RDP: Suspicious File Creation

MITRE ATT&CK coverage

References

Event coverage

Rule body kusto

Stages and Predicates

Parameters

Stage 1: source

Stage 2: where

Stage 3: where

Stage 4: where

Stage 5: where

Stage 6: project

Stage 7: join

Stage 8: where where FileTimestamp - NetworkTimestamp < 1h

Indicators

Output fields

Stage 1: `source`

Stage 2: `where`

Stage 3: `where`

Stage 4: `where`

Stage 5: `where`

Stage 6: `project`

Stage 7: `join`

Stage 8: `where` where FileTimestamp - NetworkTimestamp < 1h