Malicious Office (OOXML) / .XLSX — malware analysis report

Static analysis result for SHA-256 96b38114b85dcfc7…

MALICIOUS

Office (OOXML) / .XLSX

158.6 KB Created: 2021-09-20 10:27:09 UTC Authoring application: Microsoft Excel 12.0000
MD5: 48a37fecf109d57f6cf43d3c4be26629 SHA-1: 111bfd2c7dc0b81c16221d7056910e411de6a496 SHA-256: 96b38114b85dcfc751855e88d5cbd79c484839d6070ecc8387b49732e02f8542
120 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic for Applications T1204.002 Malicious File

The file is an Excel 4.0 macro sheet, identified by the OOXML_XLM_MACROSHEET heuristic. The embedded macro appears to be designed to download a second-stage payload from the URL http://www.google.com. The ClamAV detection name 'Xls.Downloader.Trojan-a0425f7f2000faff-a0425f7f2000faff-9950268-0' further supports its malicious nature as a downloader.

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.
  • ClamAV: Xls.Downloader.Trojan-a0425f7f2000faff-a0425f7f2000faff-9950268-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Trojan-a0425f7f2000faff-a0425f7f2000faff-9950268-0

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.bin
7ac66e9e7cd8033ed92dd2a7e2eac2226b2e088c1616ef5310c726ddace313d0		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 871 bytes

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