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

Static analysis result for SHA-256 3d1299af89f53fb4…

MALICIOUS

Office (OOXML) / .XLSM

34.2 KB Created: 2021-03-01 12:21:59 UTC Authoring application: 16.0300
MD5: b19a1275e0d7a2f2159312f4b3b77dc8 SHA-1: 948dce4cfa305a0defca8d7ae97e73b1be850fb0 SHA-256: 3d1299af89f53fb446d7190a275b267e2b9d6a7d1f36981e2663c30f51e6fb64
210 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1204.002 Malicious File T1105 Ingress Tool Transfer

This XLSM file contains both VBA macros and Excel 4.0 macros. The VBA script utilizes the URLDownloadToFileA function to download a second-stage payload from a URL that is obfuscated within the document body. The Excel 4.0 macros also contain dangerous functions like RETURN, which can be used to execute arbitrary code. The combination of these techniques strongly suggests a downloader or droppper functionality.

Heuristics 6

  • URLDownloadToFile in VBA critical OLE_VBA_DOWNLOAD
    URLDownloadToFile in VBA
  • 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.
  • Dangerous XLM formula APIs: 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.
  • VBA project inside OOXML medium OOXML_VBA
    Document contains vbaProject.bin — VBA macros present
  • 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
    • http://schemas.openxmlformats.org/markup-compatibility/2006
    • http://schemas.microsoft.com/office/spreadsheetml/2009/9/ac

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
8a974090e34b01296ac86575d647b594fe49413bb638d4b7685e9d37fb66da1f		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 2702 bytes
vbaProject_00.bin
55f6305f17adeee33a63043714c7d7492bcb5dc38a0db661143bea7eb6e9ea6c		 vba-project OOXML VBA project: xl/vbaProject.bin 20992 bytes
xlm_sheet_00.xml
c05631a0df71609a4d5e5ff00c50349f438558aa33730b995c651d0e3f25def3		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 989 bytes

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