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

Static analysis result for SHA-256 f798e0d1df1621b2…

MALICIOUS

Office (OOXML) / .XLSM

252.8 KB Created: 2021-08-16 09:36:27 UTC Authoring application: Microsoft Excel 12.0000
MD5: 0f876c50f26f4b51a8494917ca26c8c9 SHA-1: e314fca1c2e6ff3a7ba538c06add4a8d4bbedc87 SHA-256: f798e0d1df1621b2336c292f6b6f58e391a3c6b15701ab907dfd231325fee04f
190 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File T1059.001 PowerShell

The file is an XLSM document containing Excel 4.0 macros. The macros utilize dangerous functions like EXEC and FOPEN to write a script to disk and then execute it. Specifically, the macro reconstructs the path 'C:\ProgramData\waAaiLpPejELgy.sct' and writes content to it, which is then likely executed. This indicates 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, 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.
  • 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
db384f7b61ccff7d104a03dc874492878bab3577d1ef989857747caea9eb8ff3		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 748115 bytes

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