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

Static analysis result for SHA-256 02d173c5df66313e…

MALICIOUS

Office (OOXML) / .XLSM

110.5 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300
MD5: 8b242e226ff0378ff50ecdb6db2e2f47 SHA-1: f1a288193f510964602d634e86f186651c2a55c6 SHA-256: 02d173c5df66313e059863e96378097c8e1b9b16a8e3fd0eba2860b7c74ff8a0
190 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The sample is an XLSM file containing both VBA and Excel 4.0 macros. The critical heuristics indicate the use of dangerous XLM functions like REGISTER and EXEC, which are commonly used to download and execute payloads. The Auto_Open macro in the VBA code likely triggers the execution of these XLM macros. The embedded URLs are highly suspicious and likely serve as the source for the second-stage payload.

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 a VBA project — 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://195.123.235.1/
    • http://45.67.230.159/
    • http://51.195.38.32/
    • http://195.123.235.1/44313,6048108796.dat
    • http://45.67.230.159/44313,6048108796.dat
    • http://51.195.38.32/44313,6048108796.dat
    • 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
6e35115a0b63947d5914d351f8de7764c2453fb6349171fc2ca7dfb17b6dac05		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 15792 bytes
vbaProject_00.bin
2b3f1633d02c099a6f30769c4961e5ea6d4184083c29bb8c5109aa9a82773a2f		 vba-project OOXML VBA project: xl/vbaProject.bin 26112 bytes
xlm_sheet_00.xml
7716a3eb3a27a54de9de01718a02a6d229ccdf0f1eb50cc2e3f6adaf9546ea16		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 4725 bytes
xlm_sheet_01.xml
efa863078546591f10559e7ec4775260a2b46f2ed03bb71ea70b51048ee05558		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet2.xml 2004 bytes

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