Office (OOXML) / .XLSX malware analysis — malicious · c6d7ef9411539a18

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 08d47d3b5832d3446f4feab417d9e13a SHA-1: ade37c49e062f19e450d40b98d46d2c01c61d633 SHA-256: c6d7ef9411539a18c9975d76c100ff2234f1a170086a0b2a5f5fcb5c9265232c

120 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic for Applications

The file is an XLSX document containing an embedded Excel 4.0 macro sheet, indicated by the OOXML_XLM_MACROSHEET and OOXML_XLSB_INTL_MACROSHEET_IN_XLSX heuristics. The macro sheet contains obfuscated commands that appear to construct and execute URLs, specifically 'http://www.ghenrope.ru'. This suggests the macro's purpose is to download and execute a second-stage payload from this external resource.

Heuristics 2

Excel 4.0 macro sheet (1 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.

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`xlm_sheet_00.bin` `1d86b3b52f2ca77e486b256d7c7d5bcd39881af7c02f6edc2a9373cc9635903a`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet1.bin	9817 bytes

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