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

Static analysis result for SHA-256 1637d7040ea6fb21…

MALICIOUS

Office (OOXML) / .XLSX

36.4 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 16.0300
MD5: 5759cfc36a3ee73510fa80a3f37da8fd SHA-1: 9bb0408869e1c4a0fd23e7927266c37363ce5aa6 SHA-256: 1637d7040ea6fb21e6669180c987895b8476433594a1390c155d49f2fc05d7e4
318 Risk Score

Malware Insights

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

This Excel 4.0 macro sheet uses dangerous functions like REGISTER and HALT, along with WinAPI calls such as DownloadToFileA and CreateDirectoryA, to likely download and execute a second-stage payload. The presence of the Auto_Open defined name and a disguised relationship path indicates an attempt to automatically execute malicious code upon opening the spreadsheet. The embedded URLs https://safedot.digital/ and https://safedot.digital/pp are the most probable destinations for the payload.

Heuristics 8

  • Excel 4.0 macro sheet (1 sheet(s)) critical OOXML_XLM_MACROSHEET
    Spreadsheet contains an Excel 4.0 (XLM) macro sheet — XLM was a major Office malware vector during 2020-2022 and evaded many VBA-focused controls before Microsoft tightened XLM defaults. Even legitimate XLM use is rare in modern workbooks.
  • Excel 4.0 macro sheet stored under disguised package path critical OOXML_XLM_DISGUISED_RELATIONSHIP
    OOXML package declares an xlMacrosheet relationship whose target is outside the canonical xl/macrosheets/ path. Excel follows the relationship type, while path-only scanners can miss the macro execution surface.
  • Excel 4.0 Auto_Open defined name critical OOXML_XLM_AUTOOPEN_DEFINEDNAME
    Workbook defines _xlnm.Auto_Open or _xlnm.Auto_Close while containing an XLM macro sheet. This is the OOXML/XLSB auto-execution shape for Excel 4.0 macros.
  • Dangerous XLM formula APIs: REGISTER, HALT critical OOXML_XLM_DANGEROUS_FN
    Excel 4.0 macro sheet uses formula APIs that call directly into Win32 (=CALL/=EXEC/=REGISTER/=FORMULA). These are the primitives used to download payloads, write files, and start processes from an XLM macro without invoking VBA.
  • Binary XLM macro sheet with WinAPI/download strings critical OOXML_XLM_BINARY_WINAPI_STRINGS
    Excel 4.0 macro sheet is stored as BIFF12/XLSB binary data and contains Win32 download or process-execution API strings such as URLDownloadToFileA, ShellExecuteA, or CreateDirectoryA. These strings are high-signal in XLM macro sheets and catch payload-download macros that XML-formula scanners cannot parse.
  • Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 1 hidden sheet(s) — hidden sheets are commonly used to conceal macro code, staging data, or intermediate payload construction
  • Call-to-action shape / download button low OOXML_DOWNLOAD_SHAPE
    Document drawing contains a call-to-action phrase ('Click Here', 'Download Now', etc.) inside a shape or text box — a common visual lure used to trick users into enabling macros or visiting a malicious URL
  • 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://safedot.digital/
    • https://safedot.digital/pp
    • http://schemas.openxmlformats.org/spreadsheetml/2006/main
    • http://schemas.microsoft.com/office/excel/2006/main
    • http://schemas.openxmlformats.org/officeDocument/2006/relationships
    • http://schemas.openxmlformats.org/markup-compatibility/2006
    • http://schemas.microsoft.com/office/spreadsheetml/2009/9/ac
    • http://schemas.microsoft.com/office/spreadsheetml/2014/revision
    • http://schemas.microsoft.com/office/spreadsheetml/2015/revision2
    • http://schemas.microsoft.com/office/spreadsheetml/2016/revision3
    • http://schemas.microsoft.com/office/spreadsheetml/2016/revision6

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
emf_00.emf
2b9e5aa22cd9d1d97ff7f1790b59d7dd1486066a19ecb5153c89c2c5abb49d07		 ooxml-emf OOXML EMF part: xl/media/image1.emf 2744 bytes
xlm_sheet_00.xml
10725f369631e329ff158b7499fcf8b049d5668df719e79eeb707f9864888bed		 xlm-macrosheet OOXML XLM macro sheet: xl/bioxr/font.png 74910 bytes

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