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

Static analysis result for SHA-256 d02c379206003f38…

MALICIOUS

Office (OOXML) / .XLSM

32.3 KB Created: 2021-03-15 12:53:22 UTC Authoring application: Microsoft Excel 16.0300
MD5: 0de2dd44e6a3da3b31a1033a01bfcbd9 SHA-1: 7dc8f709214637f37dc838903b01b71cfe2df7e7 SHA-256: d02c379206003f382b1585dcded3d2d2142372d518bb2ce070ef6156edfcf473
128 Risk Score

Malware Insights

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

The sample is an XLSM file containing Excel 4.0 macros, which are known to be used for malicious purposes. The heuristics indicate the use of dangerous XLM formula APIs like RETURN, which can be used to download and execute payloads. The presence of a hidden worksheet further suggests an attempt to conceal malicious activity. The document body contains heavily obfuscated strings that likely represent the commands executed by the macros, including calls to PowerShell and potentially other execution mechanisms.

Heuristics 4

  • 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.
  • 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 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
51d5ceb69c668d371a4c9bdae8ac666f1ffe5283372066c032a6959a65a45674		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 953 bytes

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