Qbot — Office (OOXML) / .XLSX malware analysis

Static analysis result for SHA-256 57f6a76a58c08cd5…

MALICIOUS

Office (OOXML) / .XLSX

25.2 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 14.0300
MD5: d1d654afbae48101a2ee64e0aa6a8aca SHA-1: 9ab46807c3e5e00b71a7280d24e86860dbb8099e SHA-256: 57f6a76a58c08cd58be84c33f09022c57794f392e04bc8f22f742c6de31ad768
290 Risk Score

Malware Insights

Qbot · confidence 95%

MITRE ATT&CK
T1059.005 Service Execution: Visual Basic T1204.002 Malicious File Execution: User Execution: Malicious File T1059.001 Command and Scripting Interpreter: PowerShell T1105 Ingress Tool Transfer

The sample is an Excel 4.0 macro-enabled workbook. It utilizes dangerous XLM functions like FORMULA.FILL and REGISTER to construct and execute commands. Specifically, it constructs a command to run 'rundll32.exe ,DllRegisterServer' and uses it to download a payload from multiple URLs, including 'http://wsfapp.cn/sgmaqgktdrrz/55555555555.jpg'. The presence of these functions and the download mechanism strongly indicate a dropper functionality, consistent with the Qbot family. The ClamAV detection further supports this attribution.

Heuristics 7

  • 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.
  • Excel 4.0 Auto_Open defined name critical OOXML_XLM_AUTOOPEN_DEFINEDNAME
    Workbook defines _xlnm.Auto_Open or _xlnm.Auto_Close while containing an XLM macro sheet. This is the OOXML/XLSB auto-execution shape for Excel 4.0 macros.
  • Dangerous XLM formula APIs: FORMULA.FILL, REGISTER, EXEC, HALT critical OOXML_XLM_DANGEROUS_FN
    Excel 4.0 macro sheet uses formula APIs that call directly into Win32 (=CALL/=EXEC/=REGISTER/=FORMULA). These are the primitives used to download payloads, write files, and start processes from an XLM macro without invoking VBA.
  • ClamAV: Xls.Dropper.QbotDocu12020-9818439-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Dropper.QbotDocu12020-9818439-0
  • LOLBin token sequence in document text high SE_LOLBIN_RUN_COMMAND
    Extracted document text contains a Windows script/execution tool name (PowerShell, mshta, cmd, rundll32, regsvr32, …) within 220 characters of a dangerous flag, command verb, or URL. This is a visible 'run this' instruction in HTML/PDF/RTF lure bodies, or — in macro-laden Office files — the macro's own string-pool entries appearing adjacent in extracted text.
  • Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 2 hidden sheet(s) — hidden sheets are commonly used to conceal macro code, staging data, or intermediate payload construction
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL http://schemas.openxmlformats.org/spreadsheetml/2006/main
    • http://schemas.microsoft.com/office/excel/2006/main
    • http://schemas.openxmlformats.org/officeDocument/2006/relationships
    • http://schemas.openxmlformats.org/markup-compatibility/2006
    • http://schemas.microsoft.com/office/spreadsheetml/2009/9/ac

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
2f979a9737389447373fe5a364ea44005f131f087480c2ea3176357e28c25b8d		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 5063 bytes

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