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

Static analysis result for SHA-256 cb911e54792955b8…

MALICIOUS

Office (OOXML) / .XLSX

221.0 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300
MD5: 24e5ce5d4634355d8e97b8093d9eaf2e SHA-1: b698cda7725035c4365b88a21a1eac3526909bd6 SHA-256: cb911e54792955b8ed17527c794a1870e05694007ceb80e8e217ca471cddfa05
208 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 Excel file containing Excel 4.0 macros, which are known to be used for malicious purposes. The critical heuristics indicate 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 embedded URL pointing to a .dat file suggests the macro's intent is to download a second-stage payload from the specified IP addresses. The Auto_Open macro further indicates immediate execution upon opening the document.

Heuristics 7

  • 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
  • Suspicious extracted artifact medium EXTRACTED_FILE_STATIC_TRIAGE
    One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.
  • 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://51.89.115.124/44313,6048108796.dat
    • http://185.125.231.156/44313,6048108796.dat
    • http://185.198.57.121/44313,6048108796.dat
    • http://185.125.231.156/
    • http://185.198.57.121/
    • http://51.89.115.124/
    • 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
575cff377c7ce9d2de7685d876b3a2e3b5d44fd0e98df30551dc0a89c078d748		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 2220 bytes
vbaProject_00.bin
df162bb0e02cdb3df8d86b48e2329578f3e34be5b5fa7c34dbfda6ab6006ebce		 vba-project OOXML VBA project: xl/vbaProject.bin 16896 bytes
xlm_sheet_00.xml
8958f09f916adb733f2a9e5aa612fe15f8948114cdbf5c4d71bf3f93142e5061		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 4290 bytes
xlm_sheet_01.xml
75cb5bc00f344f305f75bbbcb076dfbef840999cdacdab06b49b508e12c29f0e		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet2.xml 2140 bytes
xlm_sheet_02.xml
dde6292619407cd5e321eae6ffce78ceda2ffd7b35d4633b1ff6c5c7a78eb139		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet3.xml 1839 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 shell/COM execution token(s).

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