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

Static analysis result for SHA-256 3635a525083cccfb…

MALICIOUS

Office (OLE) / .XLS

139.5 KB Created: 2009-08-28 01:13:41 Authoring application: Microsoft Excel
MD5: f0efab6a25f3f054dcd9f2d953823e62 SHA-1: ca5a927ac70f1b5fba59addb38f5fcddaacfd3ea SHA-256: 3635a525083cccfb32795e0f21b7796a73abfa0dc510b2d656b21d441d66ed6d
200 Risk Score

Malware Insights

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

The file contains critical heuristic firings indicating the presence of Excel 4.0 (XLM) macros, specifically an Auto_Open function. The macro sheet is identified as 'XL4Poppy' and references 'Classic.Poppy by VicodinES' and 'The Narkotic Network 1998', suggesting a known legacy macro virus. The presence of the Auto_Open function and the 'RUN' API call indicates that the macro is designed to execute automatically upon opening the spreadsheet, likely to download and execute a second-stage payload. The document body also contains references to 'Book1.xls' and a path to 'xlstart', further supporting the macro's infection and execution mechanism.

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
6846cee4721cb34f415a572d6aaaf9f3f6d5c4cf096744ff6c7fcc4f552585a2		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 72838 bytes

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