Office (OOXML) / .XLSX malware analysis — malicious · e85d4839723451c0

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: b56781e00a025a503d070d0b4b474fc0 SHA-1: 40d9b9e990402b003893ddbe132954e96d75ef98 SHA-256: e85d4839723451c0b19734b7fa37eed7f1ba39a21f9d98f3c7c10a65aeb465ce

180 Risk Score

Malware Insights

MITRE ATT&CK

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

The file contains Excel 4.0 macros, identified by multiple critical heuristics. These macros are designed to download and execute secondary payloads from several URLs, including 'http://185.244.149.75/!.dat', 'http://94.140.115.47/', and 'http://111.90.147.52/'. The macros also specify paths for dropped files such as 'C:\ProgramData\Volet1.ocx', 'C:\ProgramData\Volet2.ocx', and 'C:\ProgramData\Volet3.ocx', and indicate execution via 'regsvr32' for these files. This indicates a downloader or dropper functionality.

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.
ClamAV: Xls.Downloader.Docusign112101-9908076-0 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Xls.Downloader.Docusign112101-9908076-0

Extracted artifacts 3

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`xlm_sheet_00.bin` `da2dc731c332673ca42ff47816a19690ebe0e4e6ce693a849745367eb38e7435`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet1.bin	363 bytes
`xlm_sheet_01.bin` `ee04ddfe0d28aebc9620a1c50f4941304315b841740fce013c7291d84c5d0117`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	1652 bytes
`xlm_sheet_02.bin` `a045be5eb5eb278fe3bfd4ec51e571750e3ddc7884cea959955f4598d0900797`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet2.bin	1676 bytes

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