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

Static analysis result for SHA-256 ae958f40664f6612…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:39:56 Authoring application: Microsoft Excel
MD5: 15a236693e190d9257fb6ac1461c1801 SHA-1: d00e613cf352c9e920264c6e62c0ea12c7d11779 SHA-256: ae958f40664f66127bb065518d31174b9a6ef8a85c58977f80268cc3bd32563a
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. The presence of dangerous formula APIs like RUN indicates that the macro is designed to execute arbitrary commands. While the exact command or payload is not directly visible due to obfuscation or truncation, the Auto_Open function strongly suggests an initial stage of malware execution, likely downloading and running a second-stage payload.

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
e1bf1c501cb057e576989f4d8bfe15d688914c2d7fb9eaea3b7b0e83d6840d80
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6419 bytes