dridex Office (OOXML) / .XLSX malware analysis — malicious · c7a5355292d142a1

MALICIOUS

Office (OOXML) / .XLSX

312.2 KB Created: 2021-08-09 10:17:00 UTC Authoring application: Microsoft Excel 12.0000

MD5: 5667c85d79b7c1635d7537f6ccd1b7e9 SHA-1: 88916cc28ee6610aa160cd77ee8e0a645ed2e6b2 SHA-256: c7a5355292d142a194df03e29b51a2db3bd819653d95615954b2a830bb4eb70d

298 Risk Score

Malware Insights

dridex · confidence 95%

MITRE ATT&CK

T1566.002 Spearphishing Attachment T1059.005 Visual Basic T1059.001 PowerShell T1059.003 Windows Command Shell T1105 Ingress Tool Transfer

The sample is an Excel file containing a Workbook_Open macro and Excel 4.0 macros. The Workbook_Open macro writes a script file to the user's profile directory, specifically '%ALLUSERSPROFILE%\uHSRFZoHUCNxQyP.sct'. The presence of Excel 4.0 macros and the ClamAV detection signature 'Xls.Dropper.Dridex-9893342-1' strongly indicate a Dridex dropper. The embedded URL is likely used for further stages of the attack.

Heuristics 9

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.
ClamAV: Xls.Dropper.Dridex-9893342-1 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Xls.Dropper.Dridex-9893342-1
ClamAV detection on extracted artifact critical EXTRACTED_FILE_CLAMAV

ClamAV flagged at least one file extracted from inside this sample. Even when the wrapping document carries no AV detection of its own, a hit on the carved artifact is a strong indicator the sample is a delivery vehicle.
Workbook_Open macro high OLE_VBA_WBOPEN

Workbook_Open macro
Suspicious extracted artifact high EXTRACTED_FILE_STATIC_TRIAGE

One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.
VBA project inside OOXML medium OOXML_VBA

Document contains vbaProject.bin — VBA macros present
Environ() call (env variable access) low OLE_VBA_ENVIRON

Environ() call (env variable access)
External hyperlinks (2) low OOXML_EXTERNAL_HYPERLINKS

Document contains 2 external hyperlinks — clickable URLs are stored as external relationships. First target: http://www.shipco.com/
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://www.shipco.com/

Extracted artifacts 3

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`macros.bas` `f45c3f8727cb3e61228d96c9fdb0ed4df4de2dd2c6f569eeb4f1e0d4cd52c475`	vba-macro	oletools.olevba.extract_macros (decoded VBA source from OOXML)	1041 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved macro source contains an auto-exec entry point and execution/download terms.
`vbaProject_00.bin` `97c169e7de8aba706c263ce30d8d6e0e3d68ee58c4b1e38482c42f13ac49115b`	vba-project	OOXML VBA project: xl/vbaProject.bin	14848 bytes
Detection ClamAV: Xls.Dropper.Dridex-9893342-1 Obfuscation or payload: likely Carved macro source contains an auto-exec entry point and execution/download terms.
`xlm_sheet_00.bin` `20e7ed4fec49967bad1661d521c3f4bd4739b2d17be7a7d1b82c00ca9971fa59`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	327730 bytes

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