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

Static analysis result for SHA-256 df872850ae393e3b…

MALICIOUS

Office (OLE) / .XLSX

36.5 KB Created: 2020-11-25 10:41:56 Authoring application: Microsoft Excel
MD5: 4a44c9cabbc6f0bdfd4dd415f1df960f SHA-1: 0af242353dba4538a2b361b12b97fb5c22546ab2 SHA-256: df872850ae393e3b211dd2e897ebadad5351e5a8e45322756af581064726ad32
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1204.002 Malicious File

The file contains critical heuristic firings indicating the presence of Excel 4.0 macros with an Auto_Open defined name. The `RUN` function is identified as a dangerous API within the macro, suggesting it's used to execute arbitrary commands. This points to a macro-based attack pattern designed to download and execute a secondary payload.

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
c5e76653308d3d035cc66865af9130487344cf91214dd8a2f340e53de6fde21e		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6515 bytes

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