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

Static analysis result for SHA-256 6ecab1e07a619465…

MALICIOUS

Office (OOXML) / .XLSM

77.4 KB Created: 2021-02-08 12:04:31 UTC Authoring application: 16.0300
MD5: 25183216515c9ed40031e0e059160b5b SHA-1: d0f5d2e1e8950419fcea8170a6bb7840d0249bb4 SHA-256: 6ecab1e07a619465b49ca4f2b7d1881afb94c91f3fb072dbefb81e1acca3e8c1
210 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution T1105 Ingress Tool Transfer

This XLSM file contains Excel 4.0 macros that leverage the `RETURN()` function, which is a known primitive for executing arbitrary code. The VBA code includes a call to `URLDownloadToFileA`, indicating an intent to download a second-stage payload from a remote source. The presence of hidden sheets and the use of dangerous XLM functions further support its malicious nature.

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 a VBA project — VBA macros present
  • Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 3 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
8a5b3606cd9bcfa97abb4fd3ef11b50b15f4c7229443bc158dee06d3aba6ffbd		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 3690 bytes
vbaProject_00.bin
2f8bb105a638bf915ad4d035dd9df54df9b24f9de4f495f2c97f740082bcf060		 vba-project OOXML VBA project: xl/vbaProject.bin 22528 bytes
xlm_sheet_00.xml
b9e7d2fd302a507b07af7b2853e249f073297a134f17cd3332edeccea2b14c77		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 910 bytes

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