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

Static analysis result for SHA-256 934ebca653ff2a2f…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:46:11 Authoring application: Microsoft Excel First seen: 2023-03-30
MD5: 754c2720bc293a551469a1119707d3b4 SHA-1: 355629dd7b1a25fc12264b530be5c456d30a9ef7 SHA-256: 934ebca653ff2a2f5b8d56536e90f90f353bb18c761cc5ca82fb72efe7cd4d93
140 Risk Score

Malware Insights

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

The critical heuristic OLE_XLM_AUTOOPEN_DEFINEDNAME indicates the presence of an Excel 4.0 Auto_Open macro. This macro is designed to execute automatically when the workbook is opened. The OLE_XLM_DANGEROUS_FN heuristic further confirms that the macro uses dangerous functions like RUN, suggesting it's intended to execute arbitrary code. The macro sheet likely serves as a downloader for a secondary malicious 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
56be0887017ae118bd66f25a80a2db4190133d2bded2ca2209f6865544eddba9
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6492 bytes