Office (OLE) / .XLSX malware analysis — malicious · 0a3431c3447b4396

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-27 11:46:01 Authoring application: Microsoft Excel

MD5: 3e33648d16ddd9190c16eea51b210240 SHA-1: 9fa41128ece42bedc56f9579a97014f95cca033d SHA-256: 0a3431c3447b43968301383001657eb3d8829758a2fe52b0b4bcbc91be772a01

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1203 Exploitation for Client Execution

The file contains critical heuristics indicating the presence of Excel 4.0 macros, specifically an Auto_Open defined name. This suggests the macro is designed to execute automatically upon opening the workbook. The presence of dangerous formula APIs like RUN further confirms the intent to execute arbitrary commands.

Heuristics 3

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.
XLM Auto_Open with dangerous formula APIs critical OLE_XLM_DANGEROUS_FN

Excel 4.0 macro sheet contains an Auto_Open / Auto_Close entry and dangerous XLM formula APIs that can invoke programs, write files, or transfer control without VBA.
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.

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`xlm_macros.txt` `3f3da4f0348738f31c32793f37c4c4e126115024eacbe53e78f3ad18b632a7e6`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6544 bytes

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