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

Static analysis result for SHA-256 fe30fbfaeab2d675…

MALICIOUS

Office (OOXML) / .XLSX

115.9 KB Created: 2021-03-16 13:14:06 UTC Authoring application: Microsoft Excel 16.0300
MD5: ff38939d18321eed65651b73ed0f6901 SHA-1: d61a3091aff9bc1179e1cbf4a67f097b73f5ab44 SHA-256: fe30fbfaeab2d675c3d8c2fda5f219b159f1f41a4c46a991452e09357a0aba21
120 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File T1105 Ingress Tool Transfer

The sample is an Excel file containing Excel 4.0 macros. These macros are designed to download a file from the URL 'http://gropu.eu/f/f' and execute it. The ClamAV detection 'Doc.Downloader.Trojan-bf70f023603538ee-bf70f023603538ee-9950269-0' further confirms 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: Doc.Downloader.Trojan-bf70f023603538ee-bf70f023603538ee-9950269-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.Trojan-bf70f023603538ee-bf70f023603538ee-9950269-0

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.bin
9a88a6543e0f9e4d410d12b6088aca057f04ba058a4b33f02a8c748348bef9cc		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 3386 bytes

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