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

Static analysis result for SHA-256 7797c21f3ff516ef…

MALICIOUS

Office (OOXML) / .XLSM

291.2 KB Created: 2021-10-27 10:31:49 UTC Authoring application: Microsoft Excel 12.0000
MD5: 7f1860dddf16328a520c92afc91bdb9b SHA-1: deb5381de152882abe02d5b02475587ae6841350 SHA-256: 7797c21f3ff516efe2b7b8bb00dbe9aceec4ac9b3a742763b3745b2608d5ded3
190 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File T1059.001 PowerShell T1059.003 Windows Command Shell

This Excel 4.0 macro-enabled document (.XLSM) utilizes dangerous functions like CALL, FOPEN, FWRITE, and FCLOSE to download and execute a second-stage payload. The script attempts to write to 'C:\ProgramData\OZzaYEzrIjBfnvlbRheAg\i.vbs' and then execute it using 'ShellExecute'. The use of these functions and the obfuscated nature of the script indicate a downloader or dropper functionality.

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.
  • 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: FOPEN, FWRITE, FCLOSE, CALL, RETURN 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.
  • 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
5b25c3dabd76b2542742623d9739131455bc4d89c3e13239ef67dcb20d91199e		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 2453 bytes

Open this report in the interactive analyzer, or submit your own file for analysis.