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

Static analysis result for SHA-256 5f8d446c45630cbd…

MALICIOUS

Office (OLE) / .XLS

27.5 KB Created: 2007-12-20 03:52:17 Authoring application: Microsoft Excel
MD5: 35835166123446f7a1f74defbb5b926e SHA-1: b7cf2b60d1eb83817cd28517bd7ee9e5ad56c911 SHA-256: 5f8d446c45630cbd108ed5f152cdf716809068c16a416a9516da0265f4b9dd6c
200 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution

The file is an Excel spreadsheet containing legacy Excel 4.0 (XLM) macros, specifically an Auto_Open macro. Heuristics indicate the presence of dangerous formula APIs and markers associated with known Excel macro viruses like 'Poppy' and 'Narkotic Network'. The embedded artifacts suggest the macro attempts to infect other workbooks and save them as 'Book1.xls' in the 'xlstart' directory, indicating a likely downloader or dropper functionality.

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
ec2661f1465f78503d7a3ca1c555264acdec10f0034693b69a919e67558c88a2		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 10071 bytes

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