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

Static analysis result for SHA-256 1969286899870c7a…

MALICIOUS

Office (OLE) / .XLSX

332.0 KB Created: 2006-09-16 00:00:00 Authoring application: Microsoft Excel
MD5: 8c9ba6b5015b7ac8ce206c6948ff2e8a SHA-1: e44c4c6e4768dfcf01b796063d4d19ea930752d4 SHA-256: 1969286899870c7a8165fb425051f51fce983844ddcf34c4c8f8da4770c0b60e
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, specifically an Auto_Open entry, which is a critical finding indicating automatic execution upon opening. The macros reference dangerous functions like RUN and construct a URL from concatenated strings, pointing to 'https://19racks.com.br/ds/151120.gif'. This strongly suggests the macro's purpose is to download and execute a second-stage payload, aligning with the behavior of a downloader malware.

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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