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

Static analysis result for SHA-256 48f1b972fa687632…

MALICIOUS

Office (OOXML) / .XLSM

500.8 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300
MD5: 2ce33da1d6926a2e56be1205c9c902af SHA-1: 9b3973eb9894879bdfef4c69e5397fb8916d584c SHA-256: 48f1b972fa6876326731d03c1887d7e779b84fbf6836736578c0f3e0542d8717
250 Risk Score

Malware Insights

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

This XLSM file contains Excel 4.0 macros, including the use of dangerous functions such as EXEC, which are known to be used for downloading and executing malicious payloads. The ClamAV detection of 'Xls.Downloader.IcedID' further supports its malicious nature as a downloader. No specific URLs or hashes were extracted, but the technique is indicative of a downloader.

Heuristics 6

  • 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: GOTO, EXEC, 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 4 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 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
88ffa887b07b8e32edf38a3ad38e60bfc40472d7e57fac93d84eb5e35cc51c28		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 1463 bytes
xlm_sheet_01.xml
d1b4236e56665e42c5cb5ea33b1e14ef9f790be172893074989a2e2ffe3fbe42		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet2.xml 2019 bytes
xlm_sheet_02.xml
f01c1672da3d79f026490a3b77917d26a4d61f88738537385ad3cee9ecb0ec86		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet3.xml 1448 bytes

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