Office (OOXML) malware analysis — malicious · cc262670de9e79ea

MALICIOUS

Office (OOXML)

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

MD5: 9872ef509ac3ce7f3d3ba9ba2adafc54 SHA-1: 637965b8693db22a001675368d407b44f378e6b3 SHA-256: cc262670de9e79eaf84de6b47a7ebaa5951b802b50e0546ba9e7a5391857bde6

190 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1204.002 Malicious File T1105 Ingress Tool Transfer

The sample contains multiple Excel 4.0 macro sheets that utilize dangerous functions like CALL and EXEC. These functions are used to construct a URL and download a DLL payload from 'http://145.89.127.118/images/longearthgrinch.png' to '..\jebdjkas.dll'. The payload is then executed using 'regsvr32 -silent ..\jebdjkas.dll'. The presence of hidden sheets and the Auto_Open defined name further indicate malicious intent.

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 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 3 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` `a291b91a5380a282305592d6b3a448d6bd3bcea1fb6e41b8d6ad59ea61d9115e`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml	1726 bytes
`xlm_sheet_01.xml` `a83b22ff35bad4dc301cb7e72103b7d355b2c69141f09fbe6a8897a833702b4b`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet2.xml	1431 bytes
`xlm_sheet_02.xml` `42c5f398c7afa7a09aba4313da99a81244208c8928de8f56669a07e0825dd31f`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet3.xml	1319 bytes
`xlm_sheet_03.xml` `a48e14b490a62788dd50d5a5d9dee0e5904de6f63e56d91e46c8043cfb642875`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet4.xml	1383 bytes
`xlm_sheet_04.xml` `141ec7081e46cad64abefe5429b887b120e72363a36957d526023e01fd471fcc`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet5.xml	1362 bytes
`xlm_sheet_05.xml` `40380e54c9626303edec22203f7de57c75a5d21050e025e0ed3b801c9a67e95c`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet6.xml	1422 bytes

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