Office (OLE) / .XLS malware analysis — malicious · a390df73b5c61444

MALICIOUS

Office (OLE) / .XLS

61.5 KB Created: 2006-09-16 00:00:00 Authoring application: Microsoft Excel

MD5: b1073c53d1ade04d034805f6584b2dfb SHA-1: a612eba63d014eae2f7a370b56180f46299ab6a1 SHA-256: a390df73b5c61444c493b1e5285b4067c5ac8a9a08bfeb90f5bec9e88f741ebb

160 Risk Score

Malware Insights

MITRE ATT&CK

T1218.010 System Binary Proxy Execution: Regsvr32 T1566.001 Phishing: Spearphishing Attachment T1059.005 Command and Scripting Interpreter: Visual Basic

The sample is an Excel 4.0 macro sheet (XLM) that contains an Auto_Open macro, indicating automatic execution upon opening. It employs a lure to trick the user into enabling macros by impersonating a DocuSign signing request. The critical heuristic firing indicates the use of regsvr32.exe to execute a DLL, specifically `regsvr32.exe -s C:\LotWin\LotWin2\Horsew.dll`, which is a common technique for loading malicious payloads. The embedded URL `http://ietsmetsteigerhout.nl/ywdyalqh/` is likely associated with the payload delivery.

Heuristics 5

Excel 4.0 Auto_Open defined name critical OLE_XLM_AUTOOPEN_DEFINEDNAME

oletools recovered an Auto_Open / Auto_Close entry from an Excel 4.0 macro sheet. The raw BIFF name can be tokenized or partially opaque to byte-string checks, but the recovered macro listing confirms the workbook has an XLM auto-execution entry.
LOLBin token sequence in document text high SE_LOLBIN_RUN_COMMAND

Extracted document text contains a Windows script/execution tool name (PowerShell, mshta, cmd, rundll32, regsvr32, …) within 220 characters of a dangerous flag, command verb, or URL. This is a visible 'run this' instruction in HTML/PDF/RTF lure bodies, or — in macro-laden Office files — the macro's own string-pool entries appearing adjacent in extracted text.
Excel 4.0 (XLM) macro sheet present medium OLE_XLM_AUTOOPEN

Workbook contains an Excel 4.0 macro sheet sub-stream — XLM is rarely seen in modern legitimate workbooks and was a major Office malware vector during 2020-2022.
Macro/content-enable lure medium SE_ENABLE_LURE

Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings
Document signing service impersonation lure medium SE_DOCUSIGN_LURE

Document impersonates DocuSign, Adobe Sign, or a similar signing service in a signing-request context

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`xlm_macros.txt` `146cfc47ef519efb4d93691726e27ac06a55bf61c527045234a1b7a048b11fef`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	2103 bytes

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