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

Static analysis result for SHA-256 16754b365d81375b…

MALICIOUS

Office (OLE) / .XLSX

332.0 KB Created: 2006-09-16 00:00:00 Authoring application: Microsoft Excel
MD5: 9f27d3df746d46f9e8932c2ef57c7e43 SHA-1: 3a47b4c0eba54ea2222c0a51c4c7d24a67bdb7de SHA-256: 16754b365d81375b615d1c8a6f30ab0cf0da70037c6e07839e3eabd04e11c4ef
242 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The file contains Excel 4.0 macros with an Auto_Open defined name, which is a critical indicator of malicious intent. The macros utilize dangerous functions like RUN to execute code, and a ShellExecute API reference is present. The embedded URL `https://19racks.com.br/ds/151120.gif` is likely used to download and execute a second-stage payload, as suggested by the ClamAV detection name 'Doc.Downloader'.

Heuristics 6

  • 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.
  • ClamAV: Doc.Downloader.Docusign0521-9864805-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.Docusign0521-9864805-0
  • Reference to ShellExecute API high SC_STR_SHELLEXEC
    Reference to ShellExecute API
  • 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.
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL https://19racks.com.br/ds/151120.gif�

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
4d5531650e0faf8764ddd7b14e6947143c32308cbf699d36f8845764b3b4560a		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 5603 bytes

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