Office (OOXML) / .XLSX malware analysis — malicious · 6096e290d2b9c5d1

MALICIOUS

Office (OOXML) / .XLSX

183.4 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300

MD5: 31cabbb731c94515169c96728878dfcf SHA-1: 9e6aa6a84202ea802587d894f5d0292355660839 SHA-256: 6096e290d2b9c5d1979cba04455c7dc9c57b65fd2e5fe96c3f5a551e574071e6

310 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1203 Exploitation for Client Execution T1105 Ingress Tool Transfer

This Excel file contains Excel 4.0 macros, which are known to be used for malicious purposes. The macros utilize the `REGISTER` function to call `URLDownloadToFileA`, indicating an intent to download a second-stage payload from the specified URL. The presence of hidden sheets and dangerous XLM formula APIs further supports this assessment.

Heuristics 7

Excel 4.0 macro sheet (10 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, GOTO, REGISTER, 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.
Binary XLM macro sheet with WinAPI/download strings critical OOXML_XLM_BINARY_WINAPI_STRINGS

Excel 4.0 macro sheet is stored as BIFF12/XLSB binary data and contains Win32 download or process-execution API strings such as URLDownloadToFileA, ShellExecuteA, or CreateDirectoryA. These strings are high-signal in XLM macro sheets and catch payload-download macros that XML-formula scanners cannot parse.
ClamAV: Xls.Downloader.GreenEnable06210-9869360-0 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Xls.Downloader.GreenEnable06210-9869360-0
Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET

Excel workbook contains 10 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 10

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`xlm_sheet_00.xml` `1e56e1f2eede302543e5df8b9ebfaea744b26d28977f1390ea971f4b360a26ef`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml	3222 bytes
`xlm_sheet_01.xml` `9f05fa9be829be1eefeb660a152567edb54f7c357d0db2659790a946134ef9bd`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet2.xml	1785 bytes
`xlm_sheet_02.xml` `405845b1631a0aa71b486f4418949d96bde2110bb9f06addaf0fcd75e88528c3`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet3.xml	2657 bytes
`xlm_sheet_03.xml` `43e6f6f4ebc87c4132b97fece91322592028938542550327d7113eb1c83010e5`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet4.xml	1849 bytes
`xlm_sheet_04.xml` `49dcda5b792610c41de404d2b70cfc974135ab65a439e8c738a1c9da0fcb9f77`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet5.xml	1771 bytes
`xlm_sheet_05.xml` `d36f154dba963b8e1b114a8eb7856a7559b20af161115ec9858bc4527e63792f`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet6.xml	1559 bytes
`xlm_sheet_06.xml` `84c260af46eecb368a56b6975dc52f2fe5cc18e2695b57472a4ec15bdec2c065`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet7.xml	1586 bytes
`xlm_sheet_07.xml` `ad7ce2861628a67d038db82c6e0c4f96565fd87f489a044f5b06b21d72a592e1`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet8.xml	1589 bytes
`xlm_sheet_08.xml` `b58afdef5f0f3f74593fd083f85481e37c174bf42505739468eec6cc33659cb4`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet9.xml	1582 bytes
`xlm_sheet_09.xml` `78202619198b2160503b5dd1d62f26d794ff5905704afedefc7df1582494d5b5`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.xml	1630 bytes

Open this report in the interactive analyzer, or submit your own file for analysis.