Qbot — Office (OOXML) / .XLSX malware analysis

Static analysis result for SHA-256 09ec35f3b34b62ee…

MALICIOUS

Office (OOXML) / .XLSX

1.40 MB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-04-18
MD5: 0499fc5beb5f58ba7d2f7b7bcef3eebf SHA-1: 7d1446ae277db1a9ab3a8a0edb63e1ce14b25e69 SHA-256: 09ec35f3b34b62eee0173ae7bafe483a9a2fb503ccb2681acfd318805d86069f
260 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 critical Excel 4.0 macros that utilize WinAPI functions like URLDownloadToFileA to download a payload. The macros attempt to save the payload to 'C:\ProgramData\Dis.ooccxx', 'C:\ProgramData\Disa.ooccxx', and 'C:\ProgramData\Disb.ooccxx', and then execute it using 'Regsvr32'. This indicates a downloader functionality, consistent with the Qbot family.

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.Qbot04225-9946523-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Qbot04225-9946523-0
  • Embedded OLE object medium OOXML_OLE_OBJECT
    Document contains an embedded OLE object

Extracted artifacts 4

Files carved from inside the sample during analysis.

FilenameKindSourceSize
ooxml_oleobject_00.bin
eb40d89a980ed8f3cd3be193555cc6d3c7a584d87092dbbb7c88622cfce53f9d		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/oleObject2.bin 2263040 bytes
ooxml_oleobject_00_ole10native_00.bin
45f228642570d6f2de779122b0cdd1d811accdd0ae229de173fb524415b59b67		 ole-package OOXML xl/embeddings/oleObject2.bin Ole10Native stream: Ole10Native 2243012 bytes
emf_00.emf
28a2af9cf0dcacb9693939904f250d2c6bc1017fd36bb28b549de84468d7f1ad		 ooxml-emf OOXML EMF part: xl/media/image1.emf 4486440 bytes
xlm_sheet_00.bin
93a7db27074cd61139a35d175c75cfb266ccb4e2e9814f7c11f7d2a0f484630b		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 1754 bytes

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