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

Static analysis result for SHA-256 0016ab88534b641c…

MALICIOUS

Office (OOXML) / .XLSM

25.2 KB Created: 2021-03-11 10:55:17 UTC Authoring application: Microsoft Excel 16.0300
MD5: 1c6a23e3b7a6b7c070531e7c565c375d SHA-1: bd806e43291f75946734571a96604b6cf5a8a44c SHA-256: 0016ab88534b641c433db5fc0ff34a83a21442db744577f9ab8ed6bbb1694ad8
182 Risk Score

Malware Insights

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

The sample is an XLSM file containing Excel 4.0 macros, indicated by the OOXML_XLM_MACROSHEET heuristic. The presence of an Auto_Open defined name and the use of dangerous XLM formula APIs like FORMULA suggest an attempt to automatically execute code upon opening. The document body's message prompts the user to 'Enable Editing' and 'Enable Content', a common social engineering tactic to bypass security warnings and allow the execution of the embedded macros, which likely download and execute a second-stage payload.

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.
  • Excel 4.0 Auto_Open defined name critical OOXML_XLM_AUTOOPEN_DEFINEDNAME
    Workbook defines _xlnm.Auto_Open or _xlnm.Auto_Close while containing an XLM macro sheet. This is the OOXML/XLSB auto-execution shape for Excel 4.0 macros.
  • Dangerous XLM formula APIs: FORMULA 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.
  • 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
    • http://schemas.microsoft.com/office/spreadsheetml/2014/revision
    • http://schemas.microsoft.com/office/spreadsheetml/2015/revision2
    • http://schemas.microsoft.com/office/spreadsheetml/2016/revision3
    • http://schemas.microsoft.com/office/spreadsheetml/2016/revision6

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
45506ed0bbd50144d012315658448d74cd0b457eb7c43643e89ceb7ba23a77e1		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 19978 bytes

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