Qbot — Office (OOXML) / .XLSX malware analysis

Static analysis result for SHA-256 5e7cd461086edf8d…

MALICIOUS

Office (OOXML) / .XLSX

1.42 MB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-03-29
MD5: b46220104f17a172417a86a9cfc677fe SHA-1: cadfb0f375d962367567a9b717cf55af5dae2834 SHA-256: 5e7cd461086edf8d84c13861836614e7882e182fa6bf52c868f7af38fd649682
242 Risk Score

Malware Insights

Qbot · confidence 95%

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

This Excel file contains Excel 4.0 macros that are designed to download and execute payloads. The macros utilize WinAPI functions like URLDownloadToFileA to fetch files and then use regsvr32 to execute them from the C:\ProgramData directory. This behavior is consistent with Qbot downloader activity.

Heuristics 5

  • 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.
  • Binary XLM macro sheet with WinAPI/download strings critical OOXML_XLM_BINARY_WINAPI_STRINGS
    Excel 4.0 macro sheet is stored as BIFF12/XLSB binary data and contains Win32 download or process-execution API strings such as URLDownloadToFileA, ShellExecuteA, or CreateDirectoryA. These strings are high-signal in XLM macro sheets and catch payload-download macros that XML-formula scanners cannot parse.
  • XLM payload reassembled from CHAR()/split formulas critical OOXML_XLM_REASSEMBLED_PAYLOAD
    An Excel 4.0 macro sheet builds its payload inside the formula token stream by concatenating per-character CHAR() calls and string fragments, so no WinAPI name, shell command, or URL is ever contiguous in the .bin for a literal-bytes scan to find. Reassembling the formulas recovered download/execute API names, LOLBin commands (regsvr32/rundll32/mshta/wmic/powershell), or a payload URL — the de-obfuscated download-and-run kill chain.
  • ClamAV: Xls.Downloader.Qbot02221-9940029-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Qbot02221-9940029-0
  • Large OOXML part skipped info SCAN_INCOMPLETE
    One or more high-value OOXML parts exceeded the scanner's per-entry size cap and may not have been fully inspected.

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