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

Static analysis result for SHA-256 6442cb28bfc9ab89…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:42:36 Authoring application: Microsoft Excel
MD5: a8a4cd09773ac21f54f8d8ab5695772a SHA-1: 81c93efcc6ff8c9784443dbac85b218a954816bc SHA-256: 6442cb28bfc9ab89a802ded3e302926579c1f16b60cc29f78562f343edfa767f
140 Risk Score

Malware Insights

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

The file contains Excel 4.0 macros, specifically an Auto_Open function, which is flagged as dangerous due to its use of formula APIs like RUN. This indicates an attempt to execute arbitrary code, likely to download and run a second-stage payload. The presence of an Auto_Open entry in an Excel 4.0 macro sheet is a strong indicator 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
279609dddd1fd2e92f1972f1be5cf0cef5c3b606a7a255f0b3d91670a3792de0		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6499 bytes

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