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

Static analysis result for SHA-256 0c4651a037d3705f…

MALICIOUS

Office (OOXML) / .XLSM

109.5 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 14.0300
MD5: 98eef08dea135b16c54875d8a65977ea SHA-1: 2ec872878310b38ec164a3ec4f9500f11a470a3d SHA-256: 0c4651a037d3705f3ee5001f6937c398b51d423b5e1c68f970050686adca6db7
210 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution T1105 Ingress Tool Transfer

This XLSM file contains Excel 4.0 macros, which are known to be used for malicious purposes. The macros utilize dangerous functions like EXEC and CALL to download and execute a second-stage payload from the URLs https://giftsonlinejo.com/drms/ind.html and https://kurtos.eu/drms/ind.html. The specific macro commands found are EXEC(Sheet2!AM34&"..\duron.bnm1",DllRegisterServer) and EXEC(Sheet2!AM34&"..\duron.bnm2",DllRegisterServer), indicating a clear intent to download and run external code.

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.
  • Excel 4.0 Auto_Open defined name critical OOXML_XLM_AUTOOPEN_DEFINEDNAME
    Workbook defines _xlnm.Auto_Open or _xlnm.Auto_Close while containing an XLM macro sheet. This is the OOXML/XLSB auto-execution shape for Excel 4.0 macros.
  • Dangerous XLM formula APIs: EXEC, HALT, FORMULA, WORKBOOK.HIDE, CALL 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.
  • Suspicious extracted artifact medium EXTRACTED_FILE_STATIC_TRIAGE
    One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.
  • 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 https://giftsonlinejo.com/drms/ind.html
    • https://kurtos.eu/drms/ind.html
    • 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 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
def365b5d7a87e6d02a6e16eb8f12a49fdc817651fd2675b7065c2f67b4c736b		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet2.xml 3531 bytes
xlm_sheet_01.xml
7533330654b8e753d53bb8f9ac5e758b933e3ee32dea384bde4afa6209ed2d29		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 205649 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 shell/COM execution token(s).

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