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

Static analysis result for SHA-256 a43b825a74e1888b…

MALICIOUS

Office (OLE) / .XLSX

62.5 KB Created: 2021-05-18 16:16:51 Authoring application: Microsoft Excel
MD5: 1d31d88ad2e48bc157846ba3de51988b SHA-1: c7dc0527094a12d3e6b13f4a946b47cc6084278c SHA-256: a43b825a74e1888b7b48610f398c8c8fa7e5f50c6a0781a19aabf53472767e1f
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Service Execution: Service Execution T1059.001 PowerShell: PowerShell

The critical heuristics OLE_XLM_AUTOOPEN and OLE_XLM_DANGEROUS_FN indicate the presence of Excel 4.0 macros designed to auto-execute. The macro uses the RUN function, which is a dangerous API that can execute arbitrary commands. The extracted document body contains paths that may be used by the macro to locate or stage malicious files. The macro's intent is to execute commands, likely for downloading and running a second-stage 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
34659f34746a4e3bf956186553ce7fb67884fdec7714f40c612cba3149a21b98
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 38141 bytes