Emotet — Office (OOXML) / .XLSM malware analysis

Static analysis result for SHA-256 b42ab327e24cd16c…

MALICIOUS

Office (OOXML) / .XLSM

43.6 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-03-09
MD5: 9f46ed46b4c4f709bd5d3edece1a8fe5 SHA-1: 38508beb58dfcb3bcc8744bdec309ed01ef31b2a SHA-256: b42ab327e24cd16c2de189ef22b85d3b75652e8ade5bec1e19efdb6bf46ca646
290 Risk Score

Malware Insights

Emotet · confidence 95%

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 that leverage dangerous API calls like FORMULA to construct and execute commands. The macros attempt to download a payload from multiple URLs using regsvr32.exe and an embedded COM object 'oi.ocx'. The ClamAV detection and the nature of the macro execution strongly indicate the Emotet family, which commonly uses this delivery method. The script's intent is to download and execute 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: Xls.Downloader.Emotet03221-9941299-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet03221-9941299-0
  • 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://matskigroup.com/wp-admin/nqGatgYyNskXXqEnJw/
    • http://akbakan.com/aQonQ0Rc/
    • http://cabinetcecaf.com/wp-admin/DhqUy/
    • https://cloud-ci.online/backup/dBsIP/
    • http://safecampus.net/wp-includes/YUeG3uumtePP/
    • http://hippocrates-poetry.org/10th-annual-hippocrates/uS0IeOAAuoQ7NP9cm/
    • http://digidist.com/y3/PfakjJB/
    • 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
45360b765089a5d5456631606a414b3854a3e41bf55aab6d0866eb95d5f29d8a		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 4037 bytes
xlm_sheet_01.xml
6f5cdc5224e3f5d34a78074ca17d0580c3ce9003511ea3ebd2d1242a66f92a09		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 1276 bytes
xlm_sheet_02.xml
078006edcec633560dee822f011405034d4936f79daa7b629f378bfbf28e1ba1		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet2.xml 1152 bytes

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