Qbot — Office (OOXML) / .XLSX malware analysis

Static analysis result for SHA-256 6fb82350c4cc1608…

MALICIOUS

Office (OOXML) / .XLSX

1.02 MB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-05-13
MD5: b1c4aaaf1df3577556bcc4cb7d255795 SHA-1: 20a2cb0a28394ad659ead021093780adde44557e SHA-256: 6fb82350c4cc1608d53ab07728ee99831e64d2d9352cb179b2080cb842f73e79
240 Risk Score

Malware Insights

Qbot · confidence 95%

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

The file contains Excel 4.0 macros that utilize the URLDownloadToFileA function to download payloads from multiple URLs. The macros then attempt to execute these downloaded files using Regsvr32, specifically targeting 'C:\ProgramData\Teris.OOOCCCXXX', 'C:\ProgramData\Terisa.OOOCCCXXX', and 'C:\ProgramData\Terisb.OOOCCCXXX'. This behavior is characteristic of downloader malware, and the ClamAV signature points to Qbot.

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.Downloader.Qbot-b760f03263b7c21b-9950248-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Qbot-b760f03263b7c21b-9950248-0

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.bin
f758c93ce7d0c1deff19826bef37e51afbe225a006410e8b1544c7f941e68058		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 2282 bytes

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