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

Static analysis result for SHA-256 62af5df43be6ab6a…

MALICIOUS

Office (OLE) / .XLSX

41.5 KB Created: 2020-09-28 00:53:43 Authoring application: Microsoft Excel
MD5: 8fd290ee84fe9ef651974dff762f44e2 SHA-1: 2ae76711d548f38ecedd7f7806936be7118e44f3 SHA-256: 62af5df43be6ab6a1bca02e1859a8899a70f3c04f28e011ac44f9bad0bdcc2d5
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 defined name, which is a critical finding. The presence of dangerous formula APIs like RUN indicates that the macro is designed to execute arbitrary commands. This strongly suggests the file is a downloader or dropper for 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
50a8ee5a9b890900b321d2ce315cb795efab2dfc1ae32427ea6dceb0c1d9f935		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 8131 bytes

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