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

Static analysis result for SHA-256 9b1c03b0cca23a94…

MALICIOUS

Office (OLE) / .XLSX

469.0 KB Created: 2006-09-16 00:00:00 Authoring application: Microsoft Excel
MD5: 2b0e8b9cee363d0d50b3501f6e99849b SHA-1: 1a2e1545d7bd19940e9db02795d093ed577e32e5 SHA-256: 9b1c03b0cca23a94f2d6988c66eb0d246ec2648623765e83dbf20548ac874837
140 Risk Score

Malware Insights

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

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical finding. The macro sheet contains a reference to a URL, 'http://StarWmineiro.ch/casrtnoar/count.php', which is likely used to download and execute a second-stage payload. The presence of the Auto_Open macro and the external URL strongly suggests a malicious intent to compromise the user's system.

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
877b24336da75137a3a99cda7752c4a2d3bef2725374cfe3b531d5b368960619		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 14228 bytes

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