Emotet Office (OOXML) / .XLSM malware analysis — malicious · 079cb29d21bf28a7

MALICIOUS

Office (OOXML) / .XLSM

33.6 KB Created: 2015-06-05 18:17:20 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-03-16

MD5: e31715b937312d08132c1579178657c8 SHA-1: 3421b86f813169ff67d11c8fbe1db2a5ae95b472 SHA-256: 079cb29d21bf28a7d404ceec3fc270eb1f7ba9de50e6f3e4ff68ef4447319375

290 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK

T1059.005 Visual Basic T1218.010 System Binary Proxy Execution: Regsvr32

The sample is an Excel 4.0 macro-enabled spreadsheet (XLSM) that contains critical heuristics indicating the use of dangerous XLM formula APIs like FORMULA, CALL, and EXEC. The embedded script explicitly constructs URLs and uses regsvr32.exe to download and execute a second-stage payload from one of the provided URLs. The ClamAV signature also identifies it as an Emotet downloader.

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: Xls.Downloader.Emotet03222-9941788-0 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Xls.Downloader.Emotet03222-9941788-0
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 https://www.alejandrovillar.com/MSL/eKDWjpa4OHRxpysOTFe/
- https://alexetaurore.com/wanted/pfFtzaJovICU81kfuUp/
- http://balibuli.hu/cgi-bin/WDDM0VHSK4VcOFmU/
- https://al-brik.com/vb-w/U/
- https://alejandrastamateas.com/web/ZxA3zHwsH3r/
- http://ayursoukhya.org/wp-includes/XI35qPGHvszZ1u/
- https://aldibiki.com/prettyPhoto/gLFRzQV0VunO/
- 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.

Filename	Kind	Source	Size
`xlm_sheet_00.xml` `db0a59e4a9d5995912532cf04297a579397bf9cc37c53dfcf4ddd0de285133c8`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml	4122 bytes

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