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

Static analysis result for SHA-256 19cd4b623eda1fff…

MALICIOUS

Office (OOXML) / .XLSM

112.1 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300
MD5: afdfb4de0b96aaef8dc36a35a5dfa2f2 SHA-1: 74de89649327bed3f186b5b050b6f348fec06e7c SHA-256: 19cd4b623eda1fff9d93f22283cc34da8d1653c9042286c00fc926561f65afd2
188 Risk Score

Malware Insights

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

The sample is an XLSM file containing Excel 4.0 macros, which are known to be used for malicious purposes. The critical heuristic 'OOXML_XLM_DANGEROUS_FN' indicates the use of dangerous XLM formula APIs like FORMULA, HALT, GOTO, REGISTER, and EXEC, which can be used to download and execute payloads. The presence of an Auto_Open macro further suggests automatic execution upon opening. The embedded URLs point to potential download locations for a second-stage payload.

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.
  • Dangerous XLM formula APIs: FORMULA, HALT, GOTO, REGISTER, EXEC 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.
  • Auto_Open macro high OLE_VBA_AUTO
    Auto_Open macro
  • VBA project inside OOXML medium OOXML_VBA
    Document contains vbaProject.bin — VBA macros present
  • Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 3 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 — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL http://2.56.244.189/44313,6048108796.dat
    • http://51.254.164.244/44313,6048108796.dat
    • http://190.14.37.36/44313,6048108796.dat
    • http://2.56.244.189/
    • http://190.14.37.36/
    • http://51.254.164.244/
    • 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
    • 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/spreadsheetml/2016/revision6

Extracted artifacts 5

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
336c54ce55c4f97b2e578c36c24779a5cbf4053bf1babc3f97ec244f65df85ae		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 1451 bytes
vbaProject_00.bin
55add589d911bf92678dc48c8e8c0be1cdadf2db4eeb434c96e8acd620b130ca		 vba-project OOXML VBA project: xl/vbaProject.bin 16384 bytes
xlm_sheet_00.xml
64e724613850f858063c18423d9e364ac4664c4d306d77d2b8755ced2240473a		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 3795 bytes
xlm_sheet_01.xml
195a22194deb18d457e7a276044a8954c5a468f56b51b6a1ff34e52b2b6585ae		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet2.xml 2129 bytes
xlm_sheet_02.xml
790f162dfe4d36146f6098416bb54d0d0a33d67d88c8fea35d57cce261bdd8f0		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet3.xml 1943 bytes

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