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

Static analysis result for SHA-256 06b4a994cc6b9629…

MALICIOUS

Office (OOXML) / .XLSM

114.2 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300
MD5: 5ac72cad6c794e97474276ba534aa095 SHA-1: 5236650b529792d7aa754c62e1db170a62ecc13d SHA-256: 06b4a994cc6b9629775ebfcf818cd44267af85d7515980d4edc3c174ac47b6da
190 Risk Score

Malware Insights

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

The sample is an XLSM file containing an Auto_Open macro and Excel 4.0 macros. The XLM macros utilize dangerous functions like FORMULA and EXEC, indicating an intent to download and execute a second-stage payload from one of the provided URLs. The VBA code appears to be largely boilerplate or obfuscated, but the XLM macros are the primary mechanism for execution.

Heuristics 6

  • Excel 4.0 macro sheet (3 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: FORMULA, HALT, GOTO, REGISTER, 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 3 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://91.211.91.81/44313,6048108796.dat
    • http://5.34.179.36/44313,6048108796.dat
    • http://45.153.229.23/44313,6048108796.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 5

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
aa10abebc3ece39bf198cf3383ccb30417606e0a98d60e87747026c15426213c		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 2437 bytes
vbaProject_00.bin
c273c0ba9b123bfd6c5297a7692bdade93c1afc5139260c65963114883a46fd3		 vba-project OOXML VBA project: xl/vbaProject.bin 23552 bytes
xlm_sheet_00.xml
665f6c9f9b4a972fb7c9cd862f5d81f8391866e0188d24c7f028f17a82f6de37		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 4505 bytes
xlm_sheet_01.xml
c842664d4adfbab64cc38d3d12f48bc3fe942196965e9c614671ea94f3e6afd5		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet2.xml 2129 bytes
xlm_sheet_02.xml
10c797d7a3c632796484bdf562cdd2d33c46d8d630def0609945fce50d2eff68		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet3.xml 1949 bytes

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