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

Static analysis result for SHA-256 6a35fc7e42b5c40d…

MALICIOUS

Office (OOXML) / .XLSM

110.4 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300
MD5: 5f3235c2e9f620fb7685359585ad4333 SHA-1: 7c8edb262f6f8477e34321587ef5f44072d32b72 SHA-256: 6a35fc7e42b5c40dcbfe494dc0ac2b8cc94c3c88be69f7a636b97ef189e1a97e
190 Risk Score

Malware Insights

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

This Excel macro-enabled document (XLSM) contains critical Excel 4.0 macros that utilize dangerous functions like CALL and EXEC. These functions are used to download and execute a second-stage payload from one of the provided URLs, such as http://91.211.91.83/44313,6048108796.dat. The presence of an Auto_Open macro further indicates an immediate execution attempt upon opening the document.

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: 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://91.211.91.83/44313,6048108796.dat
    • http://190.14.37.46/44313,6048108796.dat
    • http://185.244.149.204/44313,6048108796.dat
    • http://91.211.91.83/
    • http://190.14.37.46/
    • http://185.244.149.204/
    • 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
75218b3f0bb17eeec5572784caf45beb820d0c1786c79b4827590e90358f3168		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 796 bytes
vbaProject_00.bin
68abdc7272e01a8d5f23efd6d2f6ad7622be560008d64f00989b7abcdeaf1e49		 vba-project OOXML VBA project: xl/vbaProject.bin 13824 bytes
xlm_sheet_00.xml
7f5df2ff1665161288b5ce187d9f08cbead06b57e6e53e1569d3e38eefc6f10f		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 4285 bytes
xlm_sheet_01.xml
a5fc80b1569128bd0323daacf4b0484b147d9d37755aacc26435ea011bd9f0cd		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet2.xml 2111 bytes
xlm_sheet_02.xml
a6c079d2a564b952bdc7f60d49402489a374e91f07f8b51ef328523d2a650900		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet3.xml 1944 bytes

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