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

Static analysis result for SHA-256 b69f4bf670232c10…

MALICIOUS

Office (OLE) / .XLSX

41.0 KB Created: 2020-09-28 00:53:43 Authoring application: Microsoft Excel
MD5: d51db439ba5792a32f5466e29ac06136 SHA-1: da7bd9150899e6e44d524fd8000086cc0b88b95a SHA-256: b69f4bf670232c1076f6c05316e4b45d89728ccf61b1e8b84c45e8f40f33b6fe
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic for Applications T1566.001 Spearphishing Attachment

The file is an Excel spreadsheet containing Excel 4.0 (XLM) macros. Critical heuristics indicate the presence of an Auto_Open defined name and the use of dangerous formula APIs, specifically the RUN function. This suggests the macro is designed to execute arbitrary commands when the spreadsheet is opened, a common technique for delivering malware. No specific IOCs were extracted, but the presence of Auto_Open 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
183af64d106a6eecd2e3e42b46ba21597921193f3adf03d9ca0c6a2bb978b4fe
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 7920 bytes