Xls.Downloader.Docusign — Office (OOXML) / .XLSX malware analysis

Static analysis result for SHA-256 2d328c4c572ed4e5…

MALICIOUS

Office (OOXML) / .XLSX

97.1 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300
MD5: ca5f7e1130300dab9bcd797ce4d83d06 SHA-1: ce73a3970c8c5bcfd3d90c4540fc5cd80b6ac50d SHA-256: 2d328c4c572ed4e5f3b7915598b3ce6f0fbb25bbf7f82f37704349b1bf70e400
180 Risk Score

Malware Insights

Xls.Downloader.Docusign · confidence 85%

MITRE ATT&CK
T1204.002 User Execution: Malicious File T1059.005 Command and Scripting Interpreter: Visual Basic for Applications T1105 Ingress Tool Transfer T1129 Execution: Execution of a Shared Object File T1070.004 Indicator Removal on Host: File Deletion

The sample contains Excel 4.0 macro sheets (XLM) hidden within an XLSX file, which is a technique used to evade detection. The scripts in xlm_sheet_02.bin explicitly use 'URLDownloadTo' and 'regsvr32' to download and execute payloads from 'http://Z' (truncated) and save them as 'C:\ProgramData\Volet1.ocx', 'C:\ProgramData\Volet2.ocx', and 'C:\ProgramData\Volet3.ocx'. The ClamAV detection 'Xls.Downloader.Docusign' provides direct support for the family attribution.

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.

FilenameKindSourceSize
xlm_sheet_00.bin
30e7f1eb7b7cda9226667aa44630e34cb4e61815c9b73ffde1c06f2d016d24d9		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.bin 363 bytes
xlm_sheet_01.bin
924c95acbe52d08cb50364609116239c27cf91b6440c18d7744972648a370d60		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 2900 bytes
xlm_sheet_02.bin
e80c1b37f3c5cec1142f106d8141d8a69bae7bc3fbf9a747d153a562b95978ef		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet2.bin 1676 bytes

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