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

Static analysis result for SHA-256 d0b90f932674036a…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:47:21 Authoring application: Microsoft Excel
MD5: 7dc70ac2e92d3b9edcb519909e69aeab SHA-1: 1ed8e0946c3a1fa8d7fad0071f05427d35c803e4 SHA-256: d0b90f932674036a1bd4db4c9b050ee66f6b1147e9e6e5f5900eb25d2c8a90b6
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The file contains Excel 4.0 macros, specifically an Auto_Open function, which is a known technique for executing malicious code. The critical heuristic OLE_XLM_DANGEROUS_FN firing indicates the use of dangerous function APIs like RUN, suggesting the macro is designed to execute arbitrary commands. No specific family could be identified, but the technique is indicative of a downloader or initial execution stage.

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
b8d4b238d0c083ee2ccd262a572679de52c5c4001c3846523e3c03bc09b6f15e		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6343 bytes

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