IcedID — Office (OOXML) / .XLSM malware analysis

Static analysis result for SHA-256 3136db081c6199ab…

MALICIOUS

Office (OOXML) / .XLSM

170.6 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300
MD5: e9a06605dca76fed8eca2f63a06c3e76 SHA-1: b4c227dbe6d3869fd20e01aff299a8da2613c45c SHA-256: 3136db081c6199ab620d6e700bc34ddf45d72e9cde451d1e6b37160400c8ffdd
240 Risk Score

Malware Insights

IcedID · confidence 95%

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

The file is an XLSM document containing Excel 4.0 macros, specifically utilizing dangerous functions like FORMULA.FILL, GOTO, RETURN, and EXEC. These functions are capable of downloading and executing arbitrary code, as indicated by the ClamAV detection of 'Xls.Downloader.IcedID'. The embedded URLs are highly suspicious and likely serve as the source for the second-stage payload. The use of Excel 4.0 macros for payload delivery is characteristic of certain downloader families.

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

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