Emotet Office (OOXML) / .XLSM malware analysis — malicious · 515dffd0b42ebb26

MALICIOUS

Office (OOXML) / .XLSM

74.1 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-03-15

MD5: 87b2e6a14f87b8dbfe6817150243305c SHA-1: 8012038ea541a3b53f0081959daad5d4b796667f SHA-256: 515dffd0b42ebb26ed1820d5348106d9b39bafdeb3af58fafad59b15f6158725

250 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK

T1059.005 Visual Basic T1204.002 Malicious File T1059.001 PowerShell T1059.003 Windows Command Shell

This XLSM file contains Excel 4.0 macros, indicated by the 'OOXML_XLM_MACROSHEET' and 'OOXML_XLM_DANGEROUS_FN' heuristics. The macros are designed to download and execute a payload using the 'FORMULA' API, which is a known technique for Emotet. The reconstructed URLs point to potential download locations for the secondary payload. The presence of 'regsvr32.exe' and 'rds.ocx' suggests an attempt to register a component and potentially execute malicious code.

Heuristics 6

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.Emotet03220-9941786-0 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Xls.Downloader.Emotet03220-9941786-0
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://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.

Filename	Kind	Source	Size
`xlm_sheet_00.xml` `d89b7d38fd8a9e6e956d206d38aaf287302fa490f0a6258530e7eb1289212864`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml	3854 bytes
`xlm_sheet_01.xml` `66bfcd6f779a43381c9703ce8fb35f6a1e698ff56c3952fb486a051b7507578c`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.xml	1275 bytes
`xlm_sheet_02.xml` `c4c4b38e98fc03e63dbcaf635f5d396461ebdc6c1bd91f6bea98202893777435`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet2.xml	1213 bytes

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