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

Static analysis result for SHA-256 779b451480f9e999…

MALICIOUS

Office (OLE) / .XLSX

329.0 KB Created: 2006-09-16 00:00:00 Authoring application: Microsoft Excel
MD5: 41c52ed3c8708f5f17e87753a88dc746 SHA-1: 6ba8a3e1c78dc4688c05ef3554b4f0a0b2bc7bab SHA-256: 779b451480f9e999eb6bbdb14704deb6928dd12ed0668be082403253bfd3f4c6
242 Risk Score

Malware Insights

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

The file contains Excel 4.0 macros, specifically an Auto_Open macro, which is flagged as dangerous due to its use of the RUN function. This function is used to execute external commands or contact URLs. The macro attempts to construct a URL and execute it, indicating a downloader functionality. The embedded URL `https://bemojo.com/ds/161120.gif` is the primary indicator of compromise.

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://bemojo.com/ds/161120.gif�

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
c7e4e7ed3c1ce4a0357cad7ea2d4765567912ff9637c55ef23ac64833b3a62a6		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6274 bytes

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