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

Static analysis result for SHA-256 e28f09bba2ec672d…

MALICIOUS

Office (OOXML) / .XLSM

170.6 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300
MD5: dcaba5be9cb1f3b2e7534a7eb667a79b SHA-1: abcc40806343b4b467c04ee6ca9a98ff0fcb02ff SHA-256: e28f09bba2ec672de364825f8e4390902f829ca2e30a214bc19f3a7bdb501c21
240 Risk Score

Malware Insights

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

This XLSM file contains Excel 4.0 macros, specifically utilizing the Auto_Open function. The macros employ dangerous XLM formula APIs such as FORMULA.FILL, GOTO, RETURN, and EXEC, which are indicative of a downloader. These functions are used to directly call Win32 APIs, enabling the execution of arbitrary code. The embedded URLs suggest the sample is designed to fetch and run a second-stage payload, consistent with the ClamAV detection of 'Xls.Downloader.IcedID'.

Heuristics 5

  • Excel 4.0 macro sheet (2 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.FILL, GOTO, RETURN, EXEC 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.
  • ClamAV: Xls.Downloader.IcedID-9f1f1d193a2a2a2b-9951463-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.IcedID-9f1f1d193a2a2a2b-9951463-0
  • 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 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
2149a78df9a4c2614a77eac7e6bea8856e83727824c7253b5852e5bc49a88bc0		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 5435 bytes
xlm_sheet_01.xml
544a35c39d1128d8fefaea33fca4f9da4ed2d629958b986ed71b73a0418583c0		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet2.xml 2473 bytes

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