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

Static analysis result for SHA-256 4fa036c6b3d84504…

MALICIOUS

Office (OLE) / .XLSX

44.0 KB Created: 2020-10-14 08:50:46 Authoring application: Microsoft Excel
MD5: bc77e8976062cb85d2ce90fc99564e08 SHA-1: 9dcfe05b89d0f9525022e72c55f68ba472ba2888 SHA-256: 4fa036c6b3d84504c2d93b5a6961bb23ad8c60b8d88b5efd47ef8518df1b7fd6
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1059.003 Windows Command Shell

The file contains Excel 4.0 macros, specifically an Auto_Open macro, which is a critical indicator of malicious intent. The presence of dangerous formula APIs like RUN suggests the macro is designed to execute arbitrary commands. While the exact payload is not visible, the Auto_Open macro is a common technique for downloading and executing second-stage malware.

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
1fabe626bae30af4a21b8381b5b2fe5827f8e0a1a7b8635c3c148266486809ce		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 9176 bytes

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