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

Static analysis result for SHA-256 d0c22717dabe4a1c…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:33:31 Authoring application: Microsoft Excel
MD5: ed1503b5405bac1d3646e6ae3ff855eb SHA-1: 4c829a9d4c80d189f50ce725ae673060b1081f10 SHA-256: d0c22717dabe4a1c9197c3f7ca470dd41e27988215e01663c2c9c505d9e00f4a
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 finding. This indicates that the workbook is configured to automatically execute a macro when opened. The presence of dangerous formula APIs, including the RUN function, strongly suggests that this macro is intended to execute arbitrary commands or download and run a secondary payload. No specific family could be identified, but the technique is common for initial access.

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
d979e2a632d9e53646403f5789e661dcac3e1c8ee765d74c134d2f396777ce02
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6566 bytes