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

Static analysis result for SHA-256 b324d9b68e75e8b7…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:43:55 Authoring application: Microsoft Excel
MD5: c2e89a74ff20fd8c9bfcfd57de5cb1e7 SHA-1: 3a21dc6eded6ad332f34c8253895eb626b71d3a4 SHA-256: b324d9b68e75e8b7c5a12550c304aa0378fdb81d92e4b4b70f598a2903797a74
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The sample contains an Excel 4.0 macro sheet with an Auto_Open defined name, indicating that it will execute macros automatically upon opening. Heuristics indicate the use of dangerous formula APIs, specifically the RUN function, which is commonly used to launch external executables or scripts. The document body contains heavily obfuscated text, suggesting an attempt to hide malicious content or commands.

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
09f3e6a97a11bbdf865f85481969e8eb82390ca957d7927161432f7e109439e0		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6620 bytes

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