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

Static analysis result for SHA-256 a5b33cfeb82bbe40…

MALICIOUS

Office (OOXML) / .XLSM

30.6 KB Created: 2015-06-05 18:17:20 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-03-16
MD5: e87cd6225a0f4be4bae768305565d1de SHA-1: f18fa01eb10977e280d1d7f35e62aeeb3fb91bc1 SHA-256: a5b33cfeb82bbe40ddbf9b19554c72c6055f1a6ef62faac39d0e8d021a8cca27
290 Risk Score

Malware Insights

MITRE ATT&CK
T1218.010 System Binary Proxy Execution: Regsvr32 T1059.005 Command and Scripting Interpreter: Visual Basic 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 API functions like FORMULA to construct and execute commands. Specifically, it appears to be downloading a payload from one of the provided URLs using regsvr32.exe, as indicated by the 'SE_LOLBIN_RUN_COMMAND' heuristic and the reconstructed command line. The presence of multiple suspicious URLs suggests a downloader or droppper functionality.

Heuristics 7

  • Excel 4.0 macro sheet (1 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-9982906-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Win.Malware.Agent-9982906-0
  • 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 5 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://www.ajaxmatters.com/c7g8t/hAQX/
    • http://aopda.org/wp-content/uploads/dnQjiyCcSvTbX/
    • http://intranet.fiscaltech.com.br/wp-softwares/G2DUFrG3OIV/
    • http://topadmin.topinteriors.co.in/tabler-dist/ga2l8Ioyrba/
    • http://acsconnection.com/wMHahVuKdttKf5doY/
    • http://www.seroja.edu.my/wp-includes/xL7xTYNQ/
    • http://www.ifscapital.com.my/G1lIGo/
    • 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 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
db0a59e4a9d5995912532cf04297a579397bf9cc37c53dfcf4ddd0de285133c8		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 4122 bytes

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