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

Static analysis result for SHA-256 950a6cf6c1905493…

MALICIOUS

Office (OOXML) / .XLSM

170.9 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300
MD5: 4ce1da665a558074eb9314679b2a6bcb SHA-1: 2288727f30e436095b54995792e0b294cbb25dc1 SHA-256: 950a6cf6c19054938272c3afba9e30297c8a92a0d095bb89078edb778863d934
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 downloading and executing payloads. The ClamAV detection as 'Xls.Downloader.IcedID' further supports its malicious nature as a downloader. No specific URLs or hashes were extracted, hence the IOC list is empty.

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
5f4ba7159c1da7e493848f74e3669405dc7409a06e720ced64dc3eb8a5827a76
xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet2.xml 2902 bytes
xlm_sheet_02.xml
f29a49c753318e85f442bed44c64f292c1b7fd6c5ed8b8668c3938c69145161e
xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet3.xml 2297 bytes
xlm_sheet_03.xml
966a712c4f0f0d2f58ef2ea09ca169fd5d5278d9396ce226e09ea14a32d1074e
xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet4.xml 1477 bytes
xlm_sheet_04.xml
84368b896055b80ba37112653973d9ab4ada45ec06389956e8791ed998edcdc5
xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet5.xml 1451 bytes
xlm_sheet_05.xml
68e2eada477a01dd45889d7781ac27297df589224a5824d7ff63a37df7f5bc75
xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 1476 bytes