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

Static analysis result for SHA-256 0285ca51d78f4b98…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:30:08 Authoring application: Microsoft Excel
MD5: 329b9fe9183d8fd06c162bfd0659876b SHA-1: 95fdebbe9047c70e0ce5854acc3ce6d82f05ce72 SHA-256: 0285ca51d78f4b98af74db6a9ab9ad18f989faacfb67f33cb7b6194300e4c756
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution

The file contains Excel 4.0 macros, specifically an Auto_Open function, 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. The macro sheet itself contains obfuscated data, likely to hide the payload or execution flow.

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
fc53912191531faf1683d09992f28ee24bbd4f4275450ad07482344a2c322be9		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6409 bytes

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