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

Static analysis result for SHA-256 84e478a37ca842b7…

MALICIOUS

Office (OLE) / .XLSX

35.5 KB Created: 2020-11-25 10:35:56 Authoring application: Microsoft Excel
MD5: 17b2e05ff0efa50d05b2d6a32bb8df9c SHA-1: 410f3478e4f957052e0b34d528bb6914db2fe416 SHA-256: 84e478a37ca842b7cc2240f0d63d2e51889ad54ead65ed5513237e3a349f2005
140 Risk Score

Malware Insights

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

The sample is an Excel file containing Excel 4.0 macros, indicated by the OLE_XLM_AUTOOPEN and OLE_XLM_DANGEROUS_FN heuristics. The presence of an Auto_Open defined name suggests that the macro will execute automatically when the workbook is opened. The dangerous formula API 'RUN' was also detected, which is commonly used to launch external executables or scripts. The macro's primary function is likely to download and execute a second-stage payload, although the specific URL or execution command is not directly visible in the provided evidence.

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
530b3a2824a354b1ff6b529bd8305a00c1a31d64cb1ec377c93a26986e918446
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6573 bytes