Suspicious Network Connection from fsutil or Defender Client via network_connection

ATT&CK techniques

Priv Esc → C2

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
- T1055.012Process Hollowing
Defense Evasion
- T1055.012Process Hollowing
Cred Access
Discovery
Lateral Movement
Collection
C2
- T1071.001Web Protocols
Exfiltration
Impact

What it detects

This rule detects outbound network connections from fsutil.exe or the Defender client rmclient.exe, processes that do not normally initiate network traffic. The REMCOS watchdog component injects into these binaries to maintain a covert command-and-control channel. Such connections indicate likely process injection and should be investigated.

Reporting behind it

Related detections9 linkedT1071.001 — drag to rearrange

Suspicious SearchIndexer Outbound Network Connection after Injection

Suspicious Data Exfiltration Channel to Telegram or Discord via dns_query

Malicious C2 Domain Beacon To Akamaitechnologies Masquerade via DPRK Python Intrusion

Malicious WmRAT C2 Beacon via excerorderslist Endpoint (via proxy)

Malicious DarkGate C2 Communication via Synapse User-Agent (via proxy)

Suspicious APT29 Zulip C2 Communication via curl User-Agent (via proxy)

Suspicious PowerShell Interaction with ProgramData SysInt Log via Process Creation

Malicious NPM Backdoor C2 Beacon to Injective Telemetry Endpoint via Proxy

Suspicious C2 Beacon with Legacy MSIE User Agent

Suspicious Network Connection from fsutil or Defender Client via network_connection

Pivot detection · T1071.001 · 9 related

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

Full detection rule

Unlock this rule to view and copy it

The detection logic is included with a plan. Everything else — context, mappings and implementation details — stays free on this page.

Sign in for 3 free unlocks

Signing in gives you 3 unlocks to spend on any rule in the library. No card, and they do not expire.

Also included

Unlocked rules convert on this page — to Splunk SPL or Splunk — Raw Index SPL or Microsoft Sentinel KQL or Microsoft Sentinel ASIM ASIM KQL or Microsoft Defender XDR KQL or Elastic Security KQL or Elastic Security Lucene or Elastic Security ES|QL or CrowdStrike Falcon CQL or SentinelOne PowerQuery or Palo Alto Cortex XDR XQL or Carbon Black Cloud Platform Search or Carbon Black EDR Process Search or Google Security Operations UDM Search or IBM QRadar AQL or Sumo Logic Cloud SIEM Rules expression or Rapid7 InsightIDR LEQL or Graylog Search or OpenSearch Lucene or OpenSearch PPL PPL or Grafana Loki LogQL or SQLite SQL or Zircolite SQLite — with the log-source profile the engine picked, the field map it used, and everything it could not express. Converting a rule you have unlocked costs no further credit.

See it run on a free rule →Convert your own rule →