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

Static analysis result for SHA-256 9375e4606f408e04…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:44:11 Authoring application: Microsoft Excel
MD5: e160abfe3ad7f156422fa7e78ff96edf SHA-1: 4eb11da7f476354e422100e8ad133daf78c9abfe SHA-256: 9375e4606f408e04214ef522eb4c2dc9a0e499b5c58b05d64a434457ff4bc085
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 the macro sheet is designed to execute automatically upon opening the workbook. The presence of 'RUN=0' in the heuristic firing suggests the macro is intended to execute a command or load an external resource. While the specific command is not fully reconstructed due to truncation, the Auto_Open functionality is a common method for initial payload execution in macro-based attacks. The document body contains obfuscated text, further supporting a malicious intent.

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
60867db2c46ccfee27299b0a1ea52a2e6968203b74d53fe04051713793895405
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6667 bytes