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

Static analysis result for SHA-256 fcf51687c191134c…

MALICIOUS

Office (OLE) / .XLSX

35.5 KB Created: 2020-11-25 10:38:13 Authoring application: Microsoft Excel
MD5: cdba25277a7d790c67e75722729fa63e SHA-1: c8e766df9fccd28ceffeb270918055cd5999c35e SHA-256: fcf51687c191134c990f7954bd5e59a8fb4dc42a4d08aa8a4e2584fd7f9b58c7
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic for Applications T1059.001 PowerShell T1059.003 Windows Command Shell

The file is an Excel 4.0 macro sheet containing an Auto_Open defined name, which is a critical indicator of malicious intent. The presence of the 'RUN' function within the XLM macro suggests that the macro is designed to execute arbitrary commands upon opening. This is a common technique for downloading and executing further stages of malware. No specific family could be identified, but the execution method is clear.

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
08569669c486429f1c3018dc7ba7254534315d0cadcc3d37f4258aa9d1465e9c
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6430 bytes