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

Static analysis result for SHA-256 a4c5a561e168466c…

MALICIOUS

Office (OOXML) / .XLSX

103.4 KB
MD5: 86faf7723b797cecb668380cce38379d SHA-1: 37f03107e757c0514c91fe1bc961e03163636410 SHA-256: a4c5a561e168466cca95dcfd6228f9e371c3c41899f41c8b1b5acae07d0fc308
190 Risk Score

Malware Insights

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

The sample is an Excel 4.0 macro sheet, identified by critical heuristics. The macros utilize dangerous XLM formula APIs like FORMULA, which can be used to execute arbitrary code. The reconstructed formula strings suggest the macro is designed to download and execute a second-stage payload. No specific family could be confidently identified.

Heuristics 5

  • Excel 4.0 macro sheet (3 sheet(s)) critical OOXML_XLM_MACROSHEET
    Malformed OOXML local headers contain an Excel 4.0 (XLM) macro sheet. XLM was a major Office malware vector during 2020-2022 and is rarely used in modern legitimate workbooks.
  • Dangerous XLM formula APIs: FORMULA critical OOXML_XLM_DANGEROUS_FN
    Excel 4.0 macro sheet uses formula APIs that call directly into Win32 (=CALL/=EXEC/=REGISTER/=FORMULA).
  • ClamAV: Win.Malware.Agent-9983617-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Win.Malware.Agent-9983617-0
  • Malformed OOXML package with recoverable local headers low OOXML_MALFORMED_ZIP_LOCAL_HEADERS
    The OOXML ZIP central directory is invalid or missing, but local file headers expose a recoverable Office package. This can create parser divergence between tolerant Office/ZIP readers and scanners that rely only on the central directory.
  • 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://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 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_08.xml
931aca2f208be70d374ebb6e3b5ce84d62043710cebea4a63abc358f6e3d2cda		 xlm-macrosheet Malformed OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 3792 bytes
xlm_sheet_09.xml
1301a9b68f708ecd53476001d2adc675d5907080f1329990cc388355cfbedfbc		 xlm-macrosheet Malformed OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 1278 bytes
xlm_sheet_10.xml
103e1830b20c8ca2f2e6d51a3a81673c3dd315f160a9ecbe580bdab4d6238de1		 xlm-macrosheet Malformed OOXML XLM macro sheet: xl/macrosheets/sheet2.xml 1275 bytes

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