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

Static analysis result for SHA-256 f47e7b0d10c36052…

MALICIOUS

Office (OOXML) / .XLSX

103.5 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300
MD5: 3038fff13db53b16ff33c45394d26109 SHA-1: 887905f405cf7ff4ea0fed3bbf51049030286267 SHA-256: f47e7b0d10c3605291aefd80372a3576cfd58a50f9a5c44560e422d78a505729
290 Risk Score

Malware Insights

MITRE ATT&CK
T1204.002 Malicious File: User Execution T1059.005 PowerShell T1218.011 Signed Binary Proxy Execution: Rundll32 T1105 Ingress Tool Transfer

This XLSX file contains Excel 4.0 macros, which are known to be used for malicious purposes. The macros utilize dangerous functions like FORMULA to construct and execute commands. Specifically, it appears to be constructing a command to use rundll32.exe with the urlmon.dll to download a payload from one of the provided URLs, such as https://torostripinginc.com/old/V6BBS9ai/. The presence of hidden sheets and the use of direct Win32 API calls via XLM functions indicate a deliberate attempt to conceal malicious activity and download a second-stage payload.

Heuristics 7

  • 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.
  • 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: FORMULA 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: Win.Malware.Agent-9983617-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Win.Malware.Agent-9983617-0
  • LOLBin token sequence in document text high SE_LOLBIN_RUN_COMMAND
    Extracted document text contains a Windows script/execution tool name (PowerShell, mshta, cmd, rundll32, regsvr32, …) within 220 characters of a dangerous flag, command verb, or URL. This is a visible 'run this' instruction in HTML/PDF/RTF lure bodies, or — in macro-laden Office files — the macro's own string-pool entries appearing adjacent in extracted text.
  • Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 6 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://torostripinginc.com/old/V6BBS9ai/
    • https://dev.woodiewin.com/wp-admin/Humbse55L82p72PIbbA/
    • https://geologyadventures.com/error/vEsebODbHUw/
    • https://xxden.online/wp-content/ge6YV52pidqe/
    • https://firebirdtaclub.com/_borders/TMFaFAVVxivebh/
    • 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 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
931aca2f208be70d374ebb6e3b5ce84d62043710cebea4a63abc358f6e3d2cda		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 3792 bytes
xlm_sheet_01.xml
1301a9b68f708ecd53476001d2adc675d5907080f1329990cc388355cfbedfbc		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 1278 bytes
xlm_sheet_02.xml
103e1830b20c8ca2f2e6d51a3a81673c3dd315f160a9ecbe580bdab4d6238de1		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet2.xml 1275 bytes

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