Malicious Office (OOXML) / .XLSM — malware analysis report

Static analysis result for SHA-256 41dd8b3c547f35cd…

MALICIOUS

Office (OOXML) / .XLSM

213.5 KB Created: 2021-08-16 09:36:27 UTC Authoring application: Microsoft Excel 12.0000
MD5: d68a5f02494026ef33a1f256eb888c6d SHA-1: 7a86445dd77e3eb619aaaa92c579814fa19c4395 SHA-256: 41dd8b3c547f35cd82e8318da281cd166a5184df18ea925e2e72c70417e7374f
250 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Service Execution: Visual Basic T1204.002 Malicious File: User Execution: Malicious File T1059.001 Command and Scripting Interpreter: PowerShell T1059.003 Command and Scripting Interpreter: Windows Command Shell T1105 Ingress Tool Transfer

The file is an XLSM document containing Excel 4.0 macros. The macros utilize dangerous functions like EXEC, FOPEN, and HALT. Specifically, the EXEC function is used to run a script located at 'C:\ProgramData\cQPgiheLmZDMnL.sct'. This indicates the macro's purpose is to download and execute a second-stage payload from a local path, likely dropped by the initial macro execution. The ClamAV detection as 'Xls.Downloader.DridexCyan08210-9887648-0' further supports its role as a downloader.

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: EXEC, HALT, FOPEN, FWRITE, FCLOSE 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.Downloader.DridexCyan08210-9887648-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.DridexCyan08210-9887648-0
  • Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 1 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

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
a8d7f37d175bd9b7f2b5b1ba4017e78c0dc8a3048430f98d65156430cff7ec05		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 151622 bytes

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