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

Static analysis result for SHA-256 d43f301e16564419…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:38:51 Authoring application: Microsoft Excel
MD5: 7335a3374b81d0b38ea85e48bb6350a1 SHA-1: a5eff6cfe7a8118e9c7c31dad66a0a4802543171 SHA-256: d43f301e1656441963ff093e04a83775e9b1144408033b433b07d4382fb816dc
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1204.002 Malicious File

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical finding. This indicates the macro will execute automatically when the workbook is opened. The presence of dangerous formula APIs like RUN further suggests the macro is designed to execute arbitrary commands, likely to download and run a second-stage payload. The document body content is largely unreadable, but the macro sheet itself is the primary indicator of 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
6218ad40d0c564d68638cfb9278b6ad4a8f6144a1e31b94fe743abf84d4e3af6
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6436 bytes