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

Static analysis result for SHA-256 4474c2ccab521311…

MALICIOUS

Office (OOXML) / .XLSM

85.8 KB Created: 2021-02-01 10:09:39 UTC Authoring application: 16.0300
MD5: da2e3bbe61a0b14bbf62d7e9745206da SHA-1: 6c405449ae51f79ce488f1afa6aa7ae41f3d0a2a SHA-256: 4474c2ccab521311c533fb7c3088da9be624fc16474c2765eec2f4941a2e8557
210 Risk Score

Malware Insights

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

This malicious Excel macro-enabled document (XLSM) utilizes Excel 4.0 macros, a technique that bypasses some VBA security measures. The critical heuristic 'OOXML_XLM_DANGEROUS_FN' indicates the use of dangerous XLM formula APIs like RETURN, which are often used to download and execute payloads. The VBA script explicitly calls URLDownloadToFileA, confirming the intent to download a second-stage payload from a URL, which is then saved to a file. The presence of hidden sheets further suggests an attempt to conceal malicious activity.

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 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
e1818214fe515a79cf059f38d797e2936d844799f9b994a7350225d017873477		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 3524 bytes
vbaProject_00.bin
9c154d3efde4dcd0754240e3d6ad91b2b706961edac2319aa5ef1180a4447565		 vba-project OOXML VBA project: xl/vbaProject.bin 23040 bytes
xlm_sheet_00.xml
201f5a92efc753d99ef96af4994a292bf69c665334733ad8c10b7b4a87ca19ea		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 1094 bytes

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