Emotet — Office (OOXML) / .XLSM malware analysis

Static analysis result for SHA-256 afd98d14e1db52fa…

MALICIOUS

Office (OOXML) / .XLSM

50.5 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-03-14
MD5: e59a624ca090fe369ca52c9f53780043 SHA-1: 6b1318e86dae0372d0224a0a35d849e40336fada SHA-256: afd98d14e1db52fa8c2b19a63f517538f898877d8fab24783ce5a4ab493acfe9
290 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Service Execution: Visual Basic T1218.010 System Binary Proxy Execution: Regsvr32 T1059.001 Command and Scripting Interpreter: PowerShell T1105 Ingress Tool Transfer

This XLSM file contains Excel 4.0 macros that leverage dangerous API functions like FORMULA to download payloads from multiple URLs. The macros also construct a command to execute 'regsvr32.exe' with a remote OCX file, indicating a likely download and execution of a second-stage payload. The ClamAV detection as 'Xls.Downloader.Emotet03220-9941298-0' strongly suggests the Emotet family.

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: Xls.Downloader.Emotet03220-9941298-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet03220-9941298-0
  • 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 http://centrobilinguelospinos.com/wp-admin/VrgzWT/
    • http://bsa.iain-jember.ac.id/asset/x0hMwOPVpkQSNoS8WCN/
    • https://descontador.com.br/css/q5nrG6ua/
    • http://boardingschoolsoftware.com/backup/CtMR5Yi/
    • http://ctha.uy/cgi-bin/zGhvZLq6kSV1L1Vi/
    • http://letea.eu/wp-content/3GgF4miFZTq9/
    • http://quoctoan.c1.biz/wp-admin/j8Zu/
    • 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
b99514d31bf111baca7178f1c3b7e161c3a1df476cfbefb5ab0d85aee00a0f99		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 4031 bytes
xlm_sheet_01.xml
57ec544c624f64a940b22b418ecc97356699a87d8f5405ae8ca128da00e7393a		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 1277 bytes
xlm_sheet_02.xml
1a2bbba2a276f955ce94cee47252cbd0a00ecbdfcf526f95f8e33343bc612848		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet2.xml 1152 bytes

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