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

Static analysis result for SHA-256 bfd86e81f98da9c1…

MALICIOUS

Office (OOXML) / .XLSM

30.6 KB Created: 2021-03-16 08:29:09 UTC Authoring application: 16.0300
MD5: cdb5d6cde9bde2bcc8256b4fcca8e055 SHA-1: 9b820f27c6c46ab83a116edc156de73b08f63085 SHA-256: bfd86e81f98da9c10a7dbcd558e8d187ee7724711142fc1ef9e7f43659295bdf
88 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic for Applications T1059.001 PowerShell

The file is an XLSM document containing Excel 4.0 macros, a known technique for delivering malicious payloads. The presence of a VBA project and an Excel 4.0 macro sheet strongly suggests the execution of embedded code. While the document body is heavily obfuscated and unreadable, the critical heuristic firing on the XLM macro sheet indicates a high likelihood that the macros are designed to download and execute a secondary payload. No specific family could be identified.

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.
  • VBA project inside OOXML medium OOXML_VBA
    Document contains vbaProject.bin — VBA macros present
  • Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 2 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
d15e850b0e3ba80973e1af068bcc8b60341282086d9d7550626d277c9cef34d0		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 2509 bytes
vbaProject_00.bin
f817eb5de77bf218caf1dd21fbb6f71c498ea00c792f806d349616310af0b83e		 vba-project OOXML VBA project: xl/vbaProject.bin 23040 bytes
xlm_sheet_00.xml
c77998eae21f87e28e77a0b0752a67d2a6486bd14af15ddec5704a6fbd8a0b74		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 815 bytes

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