Suspicious DLL Written to Explorer IconCache Path

ATT&CK techniques

Initial Access → Execution

Recon
Resource Dev
Initial Access
- T1566.001Spearphishing Attachment
Execution
- T1204.002Malicious File
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule detects a DLL written to the Explorer icon cache directory using an iconcache prefixed name with a numeric suffix. In Operation ForumTroll a LNK triggered PowerShell chain dropped a payload DLL named iconcache_<4digits>.dll to this location as reported by Kaspersky. Legitimate icon cache files use the .db extension so a .dll in this path is a strong masquerading and payload staging indicator.

Reporting behind it

Related detections9 linkedT1204.002 — drag to rearrange

Suspicious Office Application Spawning Script Interpreter

Ursnif C2 Proxy Traffic Identified by Base64 URI Encoding and .avi/.images Pattern

Windows process creation: Winword launching FLTLDR.exe exploitation behavior

Windows Process Creation: EQNEDT32.EXE Used as CVE-2017-11882 Exploit Dropper Parent

Windows: Winword spawning csc.exe indicative of CVE-2017-8759 exploitation

Malicious Silent AteraAgent RMM Installation via IntegratorLogin

Suspicious Windows Script Host Execution of JavaScript from Temporary Archive Extraction Folder (via process_creation)

Suspicious PowerShell Launched by MSIX StartingScriptWrapper From WindowsApps via Process Creation (via process_creation)

Suspicious PowerShell Remote TXT Payload Download Spawned by Shortcut via LNK (via process_creation)

Suspicious DLL Written to Explorer IconCache Path

Pivot detection · T1204.002 · 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 →