XF.Classic — Office (OLE) / .XLS malware analysis

Static analysis result for SHA-256 f82ab1b4d06ccb6e…

MALICIOUS

Office (OLE) / .XLS

192.0 KB Created: 2010-02-12 09:09:52
MD5: f4644d5bd3e9a9d441aa85dab1105405 SHA-1: af7839448e58b669e239a7cd4f322aaad444ce0c SHA-256: f82ab1b4d06ccb6e3c92cd9b5a800b8c3a8ab40ec6630c35796703dfe620edba
200 Risk Score

Malware Insights

XF.Classic · confidence 95%

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

The file is an Excel 4.0 macro-enabled spreadsheet containing the 'XF.Classic' macro virus, also known as 'Poppy' or 'Narkotic Network'. Heuristics indicate the presence of an Auto_Open macro that uses dangerous functions like RUN. The document body and script fragments confirm the intent to infect other workbooks and potentially download further stages, as indicated by the presence of 'XL4Poppy' and references to 'Hydrocodone/APAP 10-650'. The macro attempts to save itself as 'Book1.xls' in the XLSTART directory, suggesting an attempt at persistence and infection of newly opened workbooks.

Heuristics 4

  • 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.
  • Legacy Excel formula macro virus marker critical OLE_XLS_FORMULA_MACRO_VIRUS
    Workbook stream contains self-identifying legacy Excel formula macro virus markers. This indicates the document carries formula macro virus content even when no VBA project or modern XLM macro-sheet structure is present.
  • 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
ca1339478f104e5316826844edbfc75664b5292615cd6f4a4717428d78fb654b		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 8055 bytes

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