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

Static analysis result for SHA-256 65fb2ca388330833…

MALICIOUS

Office (OLE) / .XLSX

31.0 KB Created: 2021-01-25 16:19:04 Authoring application: Microsoft Excel
MD5: c18a35307bf88ecae9c00daafc26aa09 SHA-1: 1e8c4b7fea2245b95be5be98656c80e0edbdb35e SHA-256: 65fb2ca388330833327a22f1231924b48d170fd0722fc905e200fd03e3b8f0a9
160 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1059.005 Visual Basic

The sample is an Excel file containing an Excel 4.0 macro sheet with an Auto_Open entry, indicating it will execute automatically when the file is opened. The document body explicitly instructs the user to 'Enable Editing' and 'Enable Content', a common social engineering tactic to bypass macro security. The presence of the Auto_Open macro and the explicit user instruction points to a macro-based malware delivery mechanism.

Heuristics 4

  • 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.
  • 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

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
aa1f5723d77634b1fdd9d3fb24991404c78a432b8f14a83b97985a897ead54f8		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 3579 bytes

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