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

Static analysis result for SHA-256 b05677b226640cec…

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: 1649121227582420975c91256690dd4d SHA-1: 1ece137e94213df7de80076847c9cfa488a2a2b6 SHA-256: b05677b226640cecda367dc0fd1ee6a8535f531cdd3bdebd911b75247a9dc397
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

The sample is an Excel macro-enabled spreadsheet (XLSM) containing Excel 4.0 macros. These macros utilize dangerous formula APIs 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 reconstructed URL for download is "http://www.ajaxmatters.com/c7g8t/hAQX/".

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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