Office (OLE) / .XLS malware analysis — malicious · bc2bddf2dec271fe

MALICIOUS

Office (OLE) / .XLS

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

MD5: b6277ff640b6d6f5f13ee10ddd5420d4 SHA-1: 5f6f976fc36628ecda91dcaed8c0e47d53859034 SHA-256: bc2bddf2dec271fe672ea14b373d706b44b1fd7cd0d7e984d3c939b59016757e

160 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1204.002 Malicious File T1059.001 PowerShell T1059.003 Windows Command Shell

The sample is an Excel 4.0 macro-enabled workbook with an Auto_Open macro. It contains a lure to enable macros, impersonating a document signing service. The macro attempts to execute 'regsvr32.exe -s C:\LotWin\LotWin2\Horsew.dll', indicating it likely downloads and executes a second-stage payload from the embedded URL http://bk.umsu.ac.id/tyjfecm/.

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` `55d2d25dd8d4a7d0990b0981be080af5d4fd314771d78e41ba9448abaa18c3b7`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	2212 bytes

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