cyberstrikeus T1027.012 LNK Icon Smuggling
Sub-technique of: T1027
High-Level Description
Adversaries may smuggle commands to download malicious payloads past content filters by hiding them within otherwise seemingly benign windows shortcut files. Windows shortcut files (.LNK) include many metadata fields, including an icon location field (also known as the IconEnvironmentDataBlock) designed to specify the path to an icon file that is to be displayed for the LNK file within a host directory.
Adversaries may abuse this LNK metadata to download malicious payloads. For example, adversaries have been observed using LNK files as phishing payloads to deliver malware. Once invoked (e.g., Malicious File), payloads referenced via external URLs within the LNK icon location field may be downloaded. These files may also then be invoked by Command and Scripting Interpreter/System Binary Proxy Execution arguments within the target path field of the LNK.
LNK Icon Smuggling may also be utilized post compromise, such as malicious scripts executing an LNK on an infected host to download additional malicious payloads.
Kill Chain Phase
- Defense Evasion (TA0005)
Platforms: Windows
What to Check
- Identify if LNK Icon Smuggling technique is applicable to target environment
- Check Windows systems for indicators of LNK Icon Smuggling
- Verify mitigations are bypassed or absent (2 known mitigations)
- Assess detection coverage (1 detection strategies)
How to Test
Manual Testing
Identify Attack Surface: Determine if the target environment is susceptible to LNK Icon Smuggling by examining the target platforms (Windows).
Assess Existing Defenses: Review whether mitigations for T1027.012 are in place. If defenses are absent or misconfigured, this technique may be exploitable.
Execute Test: Use tools and methods described in the MITRE ATT&CK page and external references below.
Note: No Atomic Red Team tests available for this technique. See Atomic Red Team GitHub for updates.
Remediation Guide
M1049 Antivirus/Antimalware
Use signatures or heuristics to detect malicious LNK and subsequently downloaded files.
M1040 Behavior Prevention on Endpoint
On Windows 10, enable Attack Surface Reduction (ASR) rules to prevent execution of potentially obfuscated scripts or payloads.
Detection
Detection Strategy for LNK Icon Smuggling
Risk Assessment
| Finding | Severity | Impact |
|---|---|---|
| LNK Icon Smuggling technique applicable | High | Defense Evasion |
CWE Categories
| CWE ID | Title |
|---|---|
| CWE-693 | Protection Mechanism Failure |