Office (OOXML) / .XLSX malware analysis — malicious · 227355e697e11cdd

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 2b0179f097d42359012464e32d2e9bfa SHA-1: 5cbb6d777df2c339af12b2df5cdc49b6baf99a43 SHA-256: 227355e697e11cdde0d3d713d6131899ffb694e8495e5b80ff2788b40a4168fe

190 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic for Applications T1204.002 Malicious File T1059.001 PowerShell

This XLSX file contains multiple Excel 4.0 macro sheets, including one with an Auto_Open defined name, indicating it is designed to execute automatically. The macros utilize dangerous XLM formula APIs like FORMULA.FILL and FORMULA, which are capable of downloading and executing arbitrary code. The reconstructed formula string suggests a complex string concatenation likely used to construct a URL or command for payload delivery. The presence of hidden sheets further supports the intent to conceal malicious activity.

Heuristics 5

Excel 4.0 macro sheet (9 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.FILL, 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.
Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET

Excel workbook contains 12 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 9

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`xlm_sheet_00.xml` `6ce4fea470c2db8d02731ed4e720a7667206a3a7a5fd5336f0d2ae7ffa98ae3d`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml	1346 bytes
`xlm_sheet_01.xml` `64f2cc196ff22987ee900268c0d1e0640245c4c549527e4f8c20cb2a7e245204`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet2.xml	2627 bytes
`xlm_sheet_02.xml` `68031f6c02089036adf57e2ef01d881dabf389a96bb176fb86695c0fb7deda50`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.xml	1277 bytes
`xlm_sheet_03.xml` `523d7bbd4547bd1e2a997ca4f87318b3e43146ca792ad5f6646974573666249d`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet2.xml	1274 bytes
`xlm_sheet_04.xml` `8fc42a49b46107122818a29c3c788c5f4da7f98f832b7cd7336c44079bff7445`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet3.xml	1277 bytes
`xlm_sheet_05.xml` `0cc34d68a6dfc34c01213dcb296c84b6bcffbf2a1ff4f58b2391e1bc34549152`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet4.xml	1274 bytes
`xlm_sheet_06.xml` `d31f8e28051ceb3adffc3dfc4d67855b80aa09d8e814e84d0fb71fb149ab54a1`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet5.xml	1274 bytes
`xlm_sheet_07.xml` `e6c5b77b0a9af449bba825200a075de48e1db4999bcd20622552c6cfac36a13b`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet6.xml	1274 bytes
`xlm_sheet_08.xml` `326f37fcf446b146631e154b00af2be442cc6cbb5880bfbe76c0a5fcd0559a4c`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet7.xml	1152 bytes

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