Emotet — Office (OOXML) / .XLSX malware analysis

Static analysis result for SHA-256 1f422f169d5c1a12…

MALICIOUS

Office (OOXML) / .XLSX

144.8 KB
MD5: e88e04f6d86b779fc8cc198879c0d3e4 SHA-1: 75fbe1c138a4443022079291f38cc6c6342c16d1 SHA-256: 1f422f169d5c1a123ff1313029b6f47fe2480db05c945034ea664ba3e21e3af6
190 Risk Score

Malware Insights

Emotet · confidence 95%

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

The sample is identified as malicious by ClamAV with the signature 'Xls.Downloader.Emotet-a5251d3d2d6d3722-9951020-0', indicating it belongs to the Emotet family. Critical heuristics confirm the presence of Excel 4.0 macro sheets and the use of dangerous XLM formula APIs like FORMULA, CALL, and EXEC, which are capable of executing arbitrary code. The embedded XLM macros appear to be constructing commands and potentially downloading additional payloads, a common characteristic of Emotet droppers.

Heuristics 5

  • Excel 4.0 macro sheet (7 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: Xls.Downloader.Emotet-a5251d3d2d6d3722-9951020-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet-a5251d3d2d6d3722-9951020-0
  • 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 7

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_07.xml
845190ff95687dd3bed60f8155a4703d187c9ac3d57c95b5f1e5fbccfcda8bf1
xlm-macrosheet Malformed OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 3818 bytes
xlm_sheet_08.xml
17a44bab46f03e771bd6542298156e3f6d09e434efc242a62b869dfb808c8fe0
xlm-macrosheet Malformed OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 1339 bytes
xlm_sheet_09.xml
e0e53f2efa6401d85f42fc271b8a5f25f093236955ae9e2f8aff086ade287b72
xlm-macrosheet Malformed OOXML XLM macro sheet: xl/macrosheets/sheet2.xml 1334 bytes
xlm_sheet_10.xml
99c0021f265b2512c81119e70583856c3b88d92cfcf4088dd76957bd454698ca
xlm-macrosheet Malformed OOXML XLM macro sheet: xl/macrosheets/sheet3.xml 1337 bytes
xlm_sheet_11.xml
505da860283599ae30bb243e4b86ce81f7bcbf678c783ee47ffef058c21fdfa5
xlm-macrosheet Malformed OOXML XLM macro sheet: xl/macrosheets/sheet4.xml 1341 bytes
xlm_sheet_12.xml
33833c2bb127cd3da704c0fa39beca9ede4ef247ba80706d40a7c8cb5fdddbee
xlm-macrosheet Malformed OOXML XLM macro sheet: xl/macrosheets/sheet5.xml 1256 bytes
xlm_sheet_13.xml
9db93655cb6fd9e30bf1d3ffbd4e22d858cd95d48236de02bbc820699d35abf8
xlm-macrosheet Malformed OOXML XLM macro sheet: xl/macrosheets/sheet6.xml 1177 bytes