Malware Insights
The critical heuristics OLE_XLM_AUTOOPEN and OLE_XLM_DANGEROUS_FN indicate the presence of an Excel 4.0 macro sheet with an Auto_Open entry that uses dangerous functions, specifically the RUN function. This strongly suggests the macro is designed to execute arbitrary commands upon opening the document. The document body contains a large amount of seemingly random characters, which could be obfuscated code or data, further supporting a malicious intent. The presence of an Auto_Open macro is a common technique for initial execution and payload delivery.
Heuristics 3
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Excel 4.0 Auto_Open defined name critical OLE_XLM_AUTOOPEN_DEFINEDNAMEoletools 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.
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XLM Auto_Open with dangerous formula APIs critical OLE_XLM_DANGEROUS_FNExcel 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.
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Excel 4.0 (XLM) macro sheet present medium OLE_XLM_AUTOOPENWorkbook 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.
| Filename | Kind | Source | Size |
|---|---|---|---|
xlm_macros.txtdbc9dcfa2477c65c1b56996ddedf7b6295618edead4acc6156e39563c4026800 |
xlm-macro | oletools.olevba.extract_all_macros (XLM macro listing) | 6689 bytes |
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