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

Static analysis result for SHA-256 96179a9e1d020d2b…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:46:35 Authoring application: Microsoft Excel
MD5: b24bdbcd9844d4438ca50bb2b93edf1d SHA-1: abb8914fbc5b467b83315cd5a1f53070fd4c94b7 SHA-256: 96179a9e1d020d2ba2e1fdaac5cffc38c0d1dc37841e9719ce5e0afd29e66c4e
140 Risk Score

Malware Insights

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

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=0 within the Auto_Open macro suggests the execution of external commands. While the exact command is not fully reconstructed due to obfuscation, the technique strongly points to a downloader or initial execution stage for further malicious activity.

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
741f4daa92c685727f0d540c12a838d58b3adc77191028978f264c9c54c7eb65
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6594 bytes