IcedID — Office (OOXML) / .XLSM malware analysis

Static analysis result for SHA-256 aca9259ef8a1da7a…

MALICIOUS

Office (OOXML) / .XLSM

288.1 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300
MD5: 30b55a9c8d6b4dd0daa146b97f2eca30 SHA-1: 4a06154a2e04f0c6ccf5d22da753a74038d030e3 SHA-256: aca9259ef8a1da7a559be169d2f6a106a86834ba54dc187ee43bb13c4317aaf1
242 Risk Score

Malware Insights

IcedID · confidence 90%

MITRE ATT&CK
T1204.002 User Execution: Malicious File T1059.005 Command and Scripting Interpreter: Visual Basic for Applications T1105 Ingress Tool Transfer

The sample is an XLSM file containing Excel 4.0 (XLM) macro sheets with an Auto_Open trigger. The extracted scripts use the FORMULA.FILL primitive to dynamically construct and execute commands, which is a typical pattern for IcedID downloaders. This is further supported by a specific ClamAV detection for Xls.Downloader.IcedID.

Heuristics 5

  • Excel 4.0 macro sheet (3 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 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://feedbackportal.email/muv/mcm.php
    • http://ns.adobe.com/xap/1.0/
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#
    • 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
xlm_sheet_00.xml
237c6acd4ab553b752aada5ab1f03984004022f014a85be8a03622d28ce57c33		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet3.xml 1079 bytes
xlm_sheet_01.xml
3f50b6515644730aa4fd110e0047795daa71f9b95ccb0328b9df6ba70abd0ff8		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 872 bytes
xlm_sheet_02.xml
47bb178d9ab7db4ba0568c0d1103d8c7e29179beaf5b760f21a8bb7b3753da39		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet2.xml 1139 bytes

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