Malicious Office (OLE) / .XLS — malware analysis report

Static analysis result for SHA-256 c0b83b92765df26c…

MALICIOUS

Office (OLE) / .XLS

61.5 KB Created: 2006-09-16 00:00:00 Authoring application: Microsoft Excel
MD5: 045899b89ef185eea3baa0a2fdf6a1a2 SHA-1: f29675396c705da72fef9eb452f1777ca07a36dc SHA-256: c0b83b92765df26c382fed68564097c14fbaf4d4b05647fb2c80a9ca39107ef1
160 Risk Score

Malware Insights

MITRE ATT&CK
T1218.010 System Binary Proxy Execution: Regsvr32 T1566.002 Phishing: Spearphishing Attachment T1059.005 Command and Scripting Interpreter: Visual Basic

The sample is an Excel 4.0 macro-enabled spreadsheet that impersonates DocuSign to trick the user into enabling macros. Upon enabling, it executes 'regsvr32.exe -s C:\LotWin\LotWin2\Horsew.dll', indicating it attempts to load and run a malicious DLL. The presence of an Auto_Open macro and the regsvr32 execution strongly suggest a downloader or initial access payload. The embedded URL is likely used for payload retrieval.

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.

FilenameKindSourceSize
xlm_macros.txt
146cfc47ef519efb4d93691726e27ac06a55bf61c527045234a1b7a048b11fef		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 2103 bytes

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