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

Static analysis result for SHA-256 bfae6865f56019d1…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-27 11:38:00 Authoring application: Microsoft Excel
MD5: d207e120784f1e7133a7fa336a4300db SHA-1: 4c7cac53ebe26f2bac89ac39cf6cab5d1f3c50e0 SHA-256: bfae6865f56019d1d9665809f9d9498e1438b47d9ab9abc8e6088a6569e080cb
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 technique for executing malicious code upon opening the document. The critical heuristic firings indicate the presence of dangerous formula APIs within the Auto_Open macro, suggesting it's designed to run arbitrary commands. No specific IOCs like URLs or hashes were extracted, but the technique itself is highly indicative of malicious intent.

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
12b7bb3fcb4a49d9c618845cb69cb231c558b55f6f23537fed2b06fb3889ad76
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6564 bytes