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

Static analysis result for SHA-256 dd40df2716a9048d…

MALICIOUS

Office (OLE) / .XLSX

36.5 KB Created: 2020-11-25 10:45:58 Authoring application: Microsoft Excel
MD5: 804223f29a41b956adb5f3d6fc79be59 SHA-1: 3c7afebd393453ffe525752774e83c636a6f4893 SHA-256: dd40df2716a9048db103ce53d0aa1c6a2b4711bfb9032bb560697d971797fcff
140 Risk Score

Malware Insights

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

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical indicator of malicious intent. The presence of dangerous formula APIs like RUN suggests the macro is designed to execute arbitrary commands. While the exact command or payload is not directly visible, the Auto_Open function is a common technique for initial execution and payload delivery in macro-based attacks. The document body contains heavily obfuscated text, further indicating an attempt to hide malicious content.

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
e4960576bc85b16066151d3cdeddc27ca3cba71bd0fc51d3f4b84578f38b0895
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6668 bytes