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

Static analysis result for SHA-256 5d11e3ed79c75a5a…

MALICIOUS

Office (OLE) / .XLS

469.0 KB Created: 2006-09-16 00:00:00 Authoring application: Microsoft Excel
MD5: 4b0bb4da6318005a27f0b807ac3445b2 SHA-1: b058adc22f84672105cc49200386cf98800d3540 SHA-256: 5d11e3ed79c75a5abc1e0ee59e10d9bfdd7b469c07543abc8e1512f03804bad0
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The critical heuristics indicate the presence of Excel 4.0 macros with an Auto_Open entry, which is a common technique for executing malicious code upon opening the document. The macro is designed to download and execute a second-stage payload from the URL http://star-mineiro.ch/casrtnoar/count.php. This suggests a macro-based downloader attack.

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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