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

Static analysis result for SHA-256 f704326387278c67…

MALICIOUS

Office (OOXML) / .XLSX

55.5 KB Created: 2021-01-27 11:13:42 UTC Authoring application: 16.0300
MD5: ed1ae51a3f47e54768591b040c536184 SHA-1: d0abf0aabbc4d1a32f3e88e6eaf528148e4af5ec SHA-256: f704326387278c67bfcf84d6e83d3009db438809591160f23329d7b7b3df0f8c
250 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File T1105 Ingress Tool Transfer

This XLSX file contains both VBA and Excel 4.0 macros. The VBA code includes a declaration for URLDownloadToFileA, indicating an intent to download a payload. The Excel 4.0 macros utilize dangerous functions like RETURN, which can be used to execute arbitrary code. The combination of these elements strongly suggests a macro-based downloader designed to fetch and run a secondary malicious file.

Heuristics 7

  • URLDownloadToFile in VBA critical OLE_VBA_DOWNLOAD
    URLDownloadToFile in VBA
  • 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.
  • Dangerous XLM formula APIs: RETURN 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.
  • Auto_Open macro high OLE_VBA_AUTO
    Auto_Open macro
  • VBA project inside OOXML medium OOXML_VBA
    Document contains vbaProject.bin — VBA macros present
  • 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
  • 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 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

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
b807b51e0fde4fe981c8e3ee5fb65176682aa157e6f81e32b086b6fc671c3d32		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 2818 bytes
vbaProject_00.bin
9289d5b1a65376ab90adb3f607ed4f1c0ba30bb5a0f3723e109e3774b4b002e6		 vba-project OOXML VBA project: xl/vbaProject.bin 21504 bytes
xlm_sheet_00.xml
a0daa305022bba319bdaedacfe1917ab0fd0075fb7e12e96472e3643acb00cc7		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 1094 bytes

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