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

Static analysis result for SHA-256 889df0499fbcb32c…

MALICIOUS

Office (OLE) / .XLSX

37.0 KB Created: 2020-11-27 11:42:42 Authoring application: Microsoft Excel
MD5: 66e149f0fc72277238a81d62a0152f12 SHA-1: 77d69c1ef28853aa3c0b3476cf099e1f36c37d0a SHA-256: 889df0499fbcb32c12b5c3bfbde7ea0ea0cdd31d39128a61ea20b641beb97181
140 Risk Score

Malware Insights

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

The file contains Excel 4.0 (XLM) macro sheets with an Auto_Open defined name, indicating an attempt to automatically execute code upon opening. The critical heuristic 'OLE_XLM_DANGEROUS_FN' specifically flags the use of dangerous formula APIs like RUN, which is known for executing arbitrary commands. This suggests the macro is designed to launch external processes or scripts. No specific family could be identified, but the technique is common for initial execution.

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
7f7c55e1a5473fe77ca818b442b253c3a6029d1647ecdce6f369b8be1017ab57		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6831 bytes

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