Qbot — Office (OOXML) / .XLSX malware analysis

Static analysis result for SHA-256 5b89a92b8292f6d8…

MALICIOUS

Office (OOXML) / .XLSX

23.6 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 14.0300
MD5: 3912faa78f6330197cd1ab31d96d89d8 SHA-1: 2da20f3cca3fd0c11666fe846ded8d0983bbf8f4 SHA-256: 5b89a92b8292f6d80859d43b1778b7f2b278552b5bb56863af7070ca485f43e0
240 Risk Score

Malware Insights

Qbot · confidence 95%

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

The file contains Excel 4.0 macros that utilize WinAPI functions such as URLDownloadToFileA and ShellExecuteA. These functions are indicative of a dropper mechanism designed to download and execute a second-stage payload, likely a Qbot variant based on the ClamAV detection name. The macro sheet reassembles a payload from CHAR() and split formulas, further supporting its role as a downloader.

Heuristics 4

  • 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.Dropper.QbotDocu12020-9818439-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Dropper.QbotDocu12020-9818439-0

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.bin
581964282792c79e613320e827a7b43dd0b0bd59b511ea08bac1e7be04d2efb4		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 27387 bytes

Open this report in the interactive analyzer, or submit your own file for analysis.