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

Static analysis result for SHA-256 c793052031b0f0d2…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-27 11:41:17 Authoring application: Microsoft Excel
MD5: 4a21670e413d9a741c29fad3f6181154 SHA-1: 7742fa2daf90ff04cc4623ebd9de51e7ee2df85b SHA-256: c793052031b0f0d2671009aa00b40ccfdd43ee3f4797fa9586ac54ae137aa4b4
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical finding. This indicates that the macro will execute automatically when the workbook is opened. The presence of dangerous formula APIs like RUN further confirms the malicious intent. The macro sheet itself contains a large amount of obfuscated data, likely to hide its true functionality, but the Auto_Open entry is a clear indicator of an attack pattern designed to execute arbitrary commands upon opening.

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
ed12e5abac5e46f2ab27ba618095ca3489773e9e17b0789dcb1040970f6603f9
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6794 bytes