Office (OLE) / .XLSX malware analysis — malicious · ffa52635336f1094

MALICIOUS

Office (OLE) / .XLSX

81.0 KB Created: 2020-05-20 08:20:55 Authoring application: Microsoft Excel

MD5: 690bae61407abdff05dd83c80c3754b1 SHA-1: 8500056897dec7815df3fd2cfda0bc6795e80b61 SHA-256: ffa52635336f109486f2062989ed372f9dc48b73da81447e56bb716a5f93943d

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1204.002 Malicious File T1059.001 PowerShell

The critical heuristics OLE_XLM_AUTOOPEN and OLE_XLM_DANGEROUS_FN indicate the presence of Excel 4.0 macros designed to execute automatically. The reconstructed URL 'http://os.mediarncbx.com/DGvqBLj' from the document body suggests the macro's intent is to download and execute a second-stage payload. The presence of the Auto_Open defined name further supports the automated execution of malicious code.

Heuristics 3

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.
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.

Filename	Kind	Source	Size
`xlm_macros.txt` `f34bc674ae59f1bfd8436596d8659e6027589f57693e0d89eff6295c4bb22c2e`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	46398 bytes

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