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

Static analysis result for SHA-256 d231866df53e0a6f…

MALICIOUS

Office (OOXML) / .XLSM

173.3 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300
MD5: 4f6aefa5a074d8dc9ff0cbdccb0b12c3 SHA-1: c1e7bf9d4b33b072edf03897132c0cc1ef4273d6 SHA-256: d231866df53e0a6ffb9fdb1c139c043ad5827374c4d357cc2f5dfce38c8d7f38
250 Risk Score

Malware Insights

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

The sample is an XLSM file containing Excel 4.0 macros, indicated by multiple critical heuristic firings. These macros utilize dangerous functions like FORMULA, GOTO, and HALT, which are known primitives for executing arbitrary code and downloading payloads. The ClamAV detection as 'Xls.Downloader.IcedID' further supports its role as a downloader, though specific family attribution is not directly supported by the provided evidence.

Heuristics 6

  • Excel 4.0 macro sheet (6 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, GOTO, HALT 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
  • Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 6 hidden sheet(s) — hidden sheets are commonly used to conceal macro code, staging data, or intermediate payload construction
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — context-specific rules above attribute URLs they actually evaluated; this rule lists URLs that were present in the bytes but were not otherwise tied to a specific finding.
    URL http://schemas.openxmlformats.org/spreadsheetml/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/excel/2006/main
    • http://schemas.microsoft.com/office/spreadsheetml/2016/revision6

Extracted artifacts 6

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
e26278d9df62929caddc39c2675d1a93c805965a35896b4c4240468b728373e2
xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 1190 bytes
xlm_sheet_01.xml
6e574d187258cfb8b214ca66385682d3f0b084f350ab4d4bac670b49a1c9b987
xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet2.xml 3126 bytes
xlm_sheet_02.xml
60860e3e942fc249672c3f297fa7f4b06db5f5d49d084784eafb2c3e4889ad39
xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet3.xml 2298 bytes
xlm_sheet_03.xml
f6023b616a33da16850bd04bca335ab61b8bf9717cbe0a8ef91527cea67ae7fd
xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet4.xml 2025 bytes
xlm_sheet_04.xml
d60ca3a864e3f818e7a00f9aa3f6fdbc180e13ef9ef26c0d3de35bf633fcfa97
xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet5.xml 1560 bytes
xlm_sheet_05.xml
dd9efeb7c324f68d06e9a7e99610df77ef935e2fc86a64fc3a473904f7bcfe45
xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 1821 bytes