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

Static analysis result for SHA-256 f3e7475bb91ed04b…

MALICIOUS

Office (OLE) / .XLSX

42.5 KB Created: 2020-10-14 08:50:46 Authoring application: Microsoft Excel
MD5: 90242ad3a23c1e84e558cea1b3799f55 SHA-1: 34b01f76f9678e747f2ce5411e8bc7c3bedb1aca SHA-256: f3e7475bb91ed04b48c0b6743ed410314f879bd90dd6a223fee7df84e31c5e77
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic for Applications T1059.001 PowerShell T1204.002 Malicious File

The sample is an Excel file containing Excel 4.0 macros, indicated by the OLE_XLM_AUTOOPEN and OLE_XLM_DANGEROUS_FN heuristics. The presence of an 'Auto_Open' defined name suggests that the macro will execute automatically when the workbook is opened. The dangerous formula APIs, specifically 'RUN=2', strongly indicate that the macro is intended to download and execute a second-stage payload. The document body is heavily obfuscated and truncated, providing no clear user-facing lure.

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.

FilenameKindSourceSize
xlm_macros.txt
03ab4366afa65b313addb49154c0664255f95f653b0e5642970ce63cb794058b		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 9020 bytes

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