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

Static analysis result for SHA-256 d5159af191700fbd…

MALICIOUS

Office (OLE) / .XLSX

36.5 KB Created: 2020-11-25 10:47:13 Authoring application: Microsoft Excel
MD5: 202a3bf802240b746eab8625c20fb7df SHA-1: 57772f07e328d9c98d5269d52f13a6999952e00f SHA-256: d5159af191700fbd10db6f17814aeebb955f3af7fc9ae4cf2678d56edaf4adf3
140 Risk Score

Malware Insights

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

The critical heuristics OLE_XLM_AUTOOPEN and OLE_XLM_DANGEROUS_FN indicate the presence of an Excel 4.0 macro sheet with an Auto_Open entry that uses dangerous functions, specifically the RUN function. This strongly suggests the macro is designed to execute arbitrary code. While no specific URLs or hashes were extracted, the presence of the Auto_Open macro is a high-priority indicator for malicious execution. The macro likely downloads and executes 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
b1992b327bdacd3c383a8d3b34d5157dc6eb4a1e589998c979557adce4ef5c85
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6504 bytes