Office (OOXML) / .XLSX malware analysis — malicious · c1ef33f32b38922d

MALICIOUS

Office (OOXML) / .XLSX

1.22 MB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-04-06

MD5: 9fa67dbfc8e9cb360827d1b37307b9bf SHA-1: ef644c73817f1f48edae760206d1306ab33db5b9 SHA-256: c1ef33f32b38922d15e1d6dadfb7e4534d3fe844fe5d668ba105fb8715f42693

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1204.002 Malicious File

The file is an Excel spreadsheet containing embedded OLE objects and Excel 4.0 macro sheets, which are critical indicators of malicious intent. The macro sheets contain obfuscated commands that appear to reference the 'C:\ProgramData' directory, likely for staging or execution of a payload. The presence of these elements strongly suggests a macro-based attack designed to execute arbitrary code.

Heuristics 3

Excel 4.0 macro sheet (3 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. The macro sheet is stored as XLSB/BIFF12 binary content, which many XML-only OOXML scanners miss.
XLSB international XLM macro sheet hidden in .xlsx critical OOXML_XLSB_INTL_MACROSHEET_IN_XLSX

OOXML package is named .xlsx but contains XLSB workbook parts and an international Excel 4.0 macro sheet. This hides XLM macro execution from scanners that trust the extension or only inspect XML worksheet parts. The technique is macro execution, not a document-parser CVE.
Embedded OLE object medium OOXML_OLE_OBJECT

Document contains an embedded OLE object

Extracted artifacts 6

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`ooxml_oleobject_00.bin` `d0ff51c01c1458568ad2f6fb078b16ec2f24b492e2d0cb89d63961ac8e529947`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/oleObject2.bin	2263040 bytes
`ooxml_oleobject_00_ole10native_00.bin` `45f228642570d6f2de779122b0cdd1d811accdd0ae229de173fb524415b59b67`	ole-package	OOXML xl/embeddings/oleObject2.bin Ole10Native stream: Ole10Native	2243012 bytes
`emf_00.emf` `28a2af9cf0dcacb9693939904f250d2c6bc1017fd36bb28b549de84468d7f1ad`	ooxml-emf	OOXML EMF part: xl/media/image1.emf	4486440 bytes
`xlm_sheet_00.bin` `c7abb6dd98096c8188e7e0811ce0b33c7a22788ce247ea47da13a5111c118793`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet2.bin	896 bytes
`xlm_sheet_01.bin` `5d7fba7dd2d2b83908bd33b4d851ba4354e4f378c01d2d10786d52969a0aba93`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet3.bin	1206 bytes
`xlm_sheet_02.bin` `94e81ca813261a411918ce32ef537fb988cd8abac174ef9e6d2978d1bf292d9f`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet1.bin	608 bytes

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