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

Static analysis result for SHA-256 ed03ded8aabe6685…

MALICIOUS

Office (OOXML) / .XLSM

180.5 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300
MD5: adf280430801a6ae8541a88db812f574 SHA-1: b5d306876990b9465c2603a5c51298f1fbd7ef54 SHA-256: ed03ded8aabe6685d536c26d55e9685a05e6e148c4c5b56b73faa5d81c9c083a
248 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Service Execution: Visual Basic T1204.002 Malicious File: User Execution: Malicious File T1105 Ingress Tool Transfer

This XLSM file contains Excel 4.0 macros, specifically utilizing the Auto_Open function and dangerous API calls like REGISTER, GOTO, and EXEC. These functions are used to download a file from the URL http://indianoci.co.uk/ufriends/support.php and save it as ..\GVer.iks. The presence of hidden sheets and the use of these low-level macro functions strongly indicate a downloader's behavior.

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: REGISTER, GOTO, EXEC, RETURN 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.
  • ClamAV: Xls.Downloader.GreenEnable0921-9893703-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.GreenEnable0921-9893703-0
  • 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 http://indianoci.co.uk/ufriends/support.php
    • 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 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
de32358813740010576ef594e725f3d26f2640c00845ed0a17b8ba18fc85c254		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 5075 bytes
xlm_sheet_01.xml
10538c9809b42c055a72aa34e238ad082907d71dbec7661eb15e1fb483a8654c		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet2.xml 2781 bytes

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