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

Static analysis result for SHA-256 c58cb92b9d48d0b4…

MALICIOUS

Office (OOXML) / .XLSX

114.8 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300
MD5: 183120c1413a287c1b379192be2d9143 SHA-1: 0829d9d2e0272fa1a5fa2bbd79fee6a7009b3732 SHA-256: c58cb92b9d48d0b4034164d533bbe0edd54be0cd7eab5fa4a5c59fded9e1e4d3
188 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic for Applications T1059.001 PowerShell T1204.002 Malicious File T1105 Ingress Tool Transfer

The sample contains Excel 4.0 macros, which are known to be used for malicious purposes. The critical heuristics indicate the use of dangerous XLM functions like REGISTER and EXEC, which are commonly used to download and execute payloads. The presence of an embedded URL pointing to a .dat file further supports this, suggesting the macro is designed to fetch and run a second-stage payload. The document body also contains a URL that aligns with the suspicious network indicators.

Heuristics 6

  • Excel 4.0 macro sheet (2 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: HALT, REGISTER, GOTO, EXEC 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 2 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://185.14.31.59/44313,6048108796.dat
    • http://45.138.157.63/44313,6048108796.dat
    • http://167.114.48.59/44313,6048108796.dat
    • http://185.14.31.59/
    • http://167.114.48.59/
    • http://45.138.157.63/
    • 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 4

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
93c5b5069f910db13d08004fd9c90d4a1d5d55d767ea4a26da2a888ea23d58c3		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 16398 bytes
vbaProject_00.bin
8cb40a0b5e5940f328e54000440cd3d6d132d980e84d59e085c3b458e3acf2f6		 vba-project OOXML VBA project: xl/vbaProject.bin 28160 bytes
xlm_sheet_00.xml
e8c6d8792e3e310b1df23866dbd173d4bec5628a83ded013e399050fdb4a128e		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 4502 bytes
xlm_sheet_01.xml
efa863078546591f10559e7ec4775260a2b46f2ed03bb71ea70b51048ee05558		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet2.xml 2004 bytes

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