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

Static analysis result for SHA-256 165a4a8894225350…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:40:14 Authoring application: Microsoft Excel
MD5: 78e71640501a87b729650b536645dfb9 SHA-1: 1b3ccf24c686ad6419840969103fce3b47c9d82d SHA-256: 165a4a88942253500f82ef8b81c04ee228c6432581ff3747813e8a4a7d8ec1a3
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a known method for executing malicious code upon opening the workbook. The presence of dangerous formula APIs like RUN further indicates malicious intent. Without further script content, the exact payload and execution method remain unclear, leading to an unknown family classification.

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
8211e66c6100dae23db4a6832fb855a9c0657ad75772a4cb863cdc562b45c94e		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6649 bytes

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