Office (OLE) / .XLS malware analysis — malicious · 4161b113430ea707

MALICIOUS

Office (OLE) / .XLS

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

MD5: 52d8ecdffcac4d0097dfa912a72ff1f3 SHA-1: c02fcb2a1eaf18c6404336cdd990b1a468623b56 SHA-256: 4161b113430ea7077a0b86ac1758e3ea749a11fb6843b4671d47e0d55468b635

160 Risk Score

Malware Insights

MITRE ATT&CK

T1218.010 System Binary Proxy Execution: Regsvr32 T1059.005 Command and Scripting Interpreter: Visual Basic T1566.001 Phishing: Spearphishing Attachment T1204.002 Malicious Link: Malicious File

The sample is an Excel 4.0 macro sheet (XLM) that uses an Auto_Open macro to execute. It contains a lure to enable macros, impersonating DocuSign. The macro attempts to execute a DLL using regsvr32.exe with the command 'regsvr32.exe -s C:\LotWin\LotWin2\Horsew.dll', and a URL 'http://grupociem.com/uyqkanfyucif/' was extracted, likely for downloading the payload.

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` `ca514918e1c8c675022f49ba3856791a601f976c7085cf5920e0fc2bfdb2d209`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	2212 bytes

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