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

Static analysis result for SHA-256 34620449b0bc2fd6…

MALICIOUS

Office (OOXML) / .XLSX

97.1 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300
MD5: 3067e994ce85bc08a2a783c78fbd68cb SHA-1: aeaebd165b8abbdc7e10a6fe224979ad47436eb8 SHA-256: 34620449b0bc2fd680e5fa3e11d9b89bf4ea9739abd4e68eabead0beda17886c
180 Risk Score

Malware Insights

Xls.Downloader.Docusign · confidence 85%

MITRE ATT&CK
T1059.005 Visual Basic for Applications T1105 Ingress Tool Transfer T1547.001 Boot or Logon Autostart Execution: Registry Run Keys / Startup Folder

The sample contains hidden Excel 4.0 macro sheets (xlm_sheet_00.bin, xlm_sheet_01.bin, xlm_sheet_02.bin) that utilize the URLDownloadToCacheFile function via 'UrlDownloadTo' to drop payloads. Specifically, the scripts attempt to download files from 'http://Z' and save them to 'C:\ProgramData\Volet1.ocx', 'C:\ProgramData\Volet2.ocx', and 'C:\ProgramData\Volet3.ocx', subsequently executing them using 'regsvr32'. The ClamAV detection 'Xls.Downloader.Docusign' directly supports 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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