IcedID — Office (OOXML) / .XLSM malware analysis

Static analysis result for SHA-256 56b6de63e55ae6d8…

MALICIOUS

Office (OOXML) / .XLSM

185.5 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300
MD5: a4e97ce76c7a39ee9fa541a3c660a333 SHA-1: e3bb71833f604da1920424049ea0c15912a6a6b7 SHA-256: 56b6de63e55ae6d81433f309af5b5d29ccfe7ec9d45c644572029256eb2c6e41
242 Risk Score

Malware Insights

IcedID · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic for Applications T1204.002 Malicious File T1059.001 PowerShell T1105 Ingress Tool Transfer

The sample is an XLSM file containing Excel 4.0 macros, which is a known vector for malware delivery. The heuristics indicate the use of dangerous XLM formula APIs like FORMULA.FILL, which are used to download payloads. The ClamAV detection as 'Xls.Downloader.IcedID' strongly suggests the IcedID family, known for its downloader capabilities. The XLM macros likely establish persistence and download a second-stage payload, aligning with the typical behavior of 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://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
4579e9d9134ee88a7a896edfcabc863e2e82e557af728eaf391ae4946f07af34		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet3.xml 1288 bytes
xlm_sheet_01.xml
0101ee9e8c3951ec575bb7566d5eddf13ee538f0fe9782373a93f2413e5887d6		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 1067 bytes
xlm_sheet_02.xml
3f1fe57153abf51373b41e259e14cd7b677ecfec1f43f73b973ae63b3ad3f3c1		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet2.xml 1332 bytes

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