IcedID — Office (OOXML) / .XLSM malware analysis

Static analysis result for SHA-256 c52b10e957f1e5e2…

MALICIOUS

Office (OOXML) / .XLSM

170.5 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300
MD5: ab9b65a2ac5c819cd40dbc25b853b185 SHA-1: a66715710b49e6cc4ddb6bf4f6f735ad6260aecf SHA-256: c52b10e957f1e5e2b90464f7e4ebf0ea6d3abdf612aa35a20f81fd10b1525fae
240 Risk Score

Malware Insights

IcedID · confidence 95%

MITRE ATT&CK
T1059.005 Service Execution: Visual Basic T1204.002 Malicious File: Malicious File T1105 Ingress Tool Transfer

The file is an Excel macro-enabled sheet (XLSM) containing Excel 4.0 macros. Heuristics indicate the use of dangerous XLM functions like FORMULA.FILL, GOTO, RETURN, and EXEC, which are commonly used to download and execute payloads. The ClamAV signature also explicitly identifies it as an IcedID downloader. The embedded document body contains IP addresses that are likely related to the payload delivery infrastructure.

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
de99fa97839e5d559ffd5543beb25297e16f5f1cc3e539445745354d3f480145		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 4771 bytes
xlm_sheet_01.xml
ec666c9d225befa7b355659a9f4b1be9fc09d89a108ceccff5430c2c3d528ed9		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet2.xml 2475 bytes

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