Office (OOXML) / .XLSX malware analysis — malicious · 5377eaa9340bcd1c

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: f1e75d45f61d42ec7ddd4289f9891c95 SHA-1: e036fee394916dc607780e8e95a1dea5e57b7feb SHA-256: 5377eaa9340bcd1c8c52c6377e740e3f6c6d2b90437c4a3d09182ffff15fa812

190 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic for Applications T1204.002 Malicious File T1059.001 PowerShell T1105 Ingress Tool Transfer

The sample contains multiple Excel 4.0 macro sheets, including one with an Auto_Open defined name, which is a common technique for executing malicious code upon opening the document. The macros utilize dangerous XLM formula APIs like FORMULA.FILL, which are capable of downloading and executing payloads. The reconstructed formula in xlm_sheet_01.xml indicates a concatenation of cell references that likely forms a URL. Two unknown reputation URLs were extracted, which are likely the sources for the second-stage payload.

Heuristics 5

Excel 4.0 macro sheet (5 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, FORMULA.FILL 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 https://biopaten.no/xeBP8Oj5/gg.html
- https://beartoothkawasaki.com/QJT19jhtwHt/gg.html
- 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 5

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`xlm_sheet_00.xml` `15fbfe55b20413f92e6ae6dcaa5199ef4834995471413702ff1b1894f486343d`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml	11346 bytes
`xlm_sheet_01.xml` `01be081374433318ab060c7d9534b134366d414e43d756214d58deb1a7557a22`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet2.xml	1807 bytes
`xlm_sheet_02.xml` `4942d78e9a4c26c9352582ba044fbdd7b5e434ac67308d3cb59b8725b48e9b99`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet3.xml	1777 bytes
`xlm_sheet_03.xml` `a6863ce46a6a991745232b05bc1b5af380056ae05155ba24221669ae920dc1d9`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet4.xml	1460 bytes
`xlm_sheet_04.xml` `7a65a9a19541a783d2364e0cc237ab353fd49b12ac69aaaae5e6996c7d787d37`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet5.xml	1558 bytes

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