Office (OOXML) / .XLSM malware analysis — malicious · 6cb9eff2c03a7064

MALICIOUS

Office (OOXML) / .XLSM

85.7 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 16.0300

MD5: e05574d2a2b00fc7b9862ad631ce3315 SHA-1: b55f7933231453358bd4e0a033a8030595412b60 SHA-256: 6cb9eff2c03a7064a655a6117cb62d4bf8694a6fab10588cac60b0781d60ca4d

190 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1203 Exploitation for Client Execution

The sample contains Excel 4.0 macros, indicated by multiple critical heuristic firings including the use of dangerous functions like FORMULA and HALT. The macros construct a URL and filename, then use the CALL function to download and execute a DLL payload from 'http://162.248.227.39/first.php' to the path '..\yeieowur.dll'. This indicates a downloader functionality.

Heuristics 5

Excel 4.0 macro sheet (6 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, HALT 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.
Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET

Excel workbook contains 1 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 6

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`xlm_sheet_00.xml` `cf1825a3b085e5c600f6e09c6c58c7f1fe259e14f9a0915f2ddf106a13735f1c`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml	5734 bytes
`xlm_sheet_01.xml` `eb4bc757f510fdbb709e0b0ba07a386090e1c129fe22ab3970899cf68507715f`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet2.xml	3904 bytes
`xlm_sheet_02.xml` `a8de137f82b4947672de2fe635459778026bf24dcdbfb1f0cb74494eefd29cdc`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.xml	1468 bytes
`xlm_sheet_03.xml` `b3ceb4b10c63c5884849d461bcfd49965268f16342b5582612850ead81276dd8`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet2.xml	1624 bytes
`xlm_sheet_04.xml` `ec2494eab5af22ebd0fab7196ed1fdd149d7271871742286d358e3c0d940ad71`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet3.xml	1693 bytes
`xlm_sheet_05.xml` `f625d4527df6181dc15064a8c07eb18e81a419a66786237111148022b3b8ee10`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet4.xml	1686 bytes

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