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

Static analysis result for SHA-256 3a08a954b5420702…

MALICIOUS

Office (OOXML) / .XLSM

35.9 KB Created: 2021-03-15 11:16:59 UTC Authoring application: 16.0300
MD5: 22c652771b8ce73627adc88d637929cf SHA-1: 014cc86b4b1421daa675c34183b7aab2c8fb231b SHA-256: 3a08a954b5420702dc1f57733dc238f9977c4dd2041749043ae3e48b36b638c6
208 Risk Score

Malware Insights

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

The sample is an XLSM file containing Excel 4.0 macros. Critical heuristics indicate the use of dangerous XLM formula APIs like RETURN, which are often used to download and execute payloads. The presence of a hidden worksheet further suggests an attempt to conceal malicious activity. The VBA project and XLM macro sheet are likely responsible for initiating the download process via URLDownloadToFile.

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://www.w3.org/1999/02/22-rdf-syntax-ns#
    • http://ns.adobe.com/xap/1.0/
    • http://purl.org/dc/elements/1.1/
    • http://ns.adobe.com/photoshop/1.0/
    • http://ns.adobe.com/xap/1.0/mm/
    • http://ns.adobe.com/xap/1.0/sType/ResourceEvent#
    • 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
0d829473dd1f86c9ea581b35498a3b87ce7dc3e27374c6fa07d474a42c0392ed		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 3014 bytes
vbaProject_00.bin
9a2e0488555bbe47e8f96bbc61bf50f27b3bb4b37481d523246f1556a6917320		 vba-project OOXML VBA project: xl/vbaProject.bin 22016 bytes
xlm_sheet_00.xml
7995a34ef099552182599a14185f8ffcb35c53e6b03675eac0da8937d8df35d8		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 992 bytes

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