Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 a9c2f27b0666affc…

MALICIOUS

Office (OLE) / .XLSX

218.0 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel First seen: 2023-02-11
MD5: 8fbaa780c9336ea8887d8949ed114799 SHA-1: 726c148c897365be9f482d0dc1fcad6929461acc SHA-256: a9c2f27b0666affc9f3cb78b5d662606cd0cb1be1c1dafd2c260ae229953b7c0
322 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1218.010 System Binary Proxy Execution: Regsvr32 T1105 Ingress Tool Transfer

The file contains Excel 4.0 macros with an Auto_Open entry, which is a critical indicator of malicious intent. The macros leverage the URLDownloadToFile API to fetch a payload, and the presence of 'regsvr32.exe' in the document text suggests its use for executing the downloaded content. ClamAV detection further confirms this as Emotet. The embedded URLs are likely sources for the second-stage payload.

Heuristics 8

  • Reference to URLDownloadToFile API critical SC_STR_URLDOWNLOAD
    Reference to URLDownloadToFile API
  • Excel 4.0 Auto_Open defined name critical OLE_XLM_AUTOOPEN_DEFINEDNAME
    oletools recovered an Auto_Open / Auto_Close entry from an Excel 4.0 macro sheet. The raw BIFF name can be tokenized or partially opaque to byte-string checks, but the recovered macro listing confirms the workbook has an XLM auto-execution entry.
  • XLM Auto_Open with dangerous formula APIs critical OLE_XLM_DANGEROUS_FN
    Excel 4.0 macro sheet contains an Auto_Open / Auto_Close entry and dangerous XLM formula APIs that can invoke programs, write files, or transfer control without VBA.
  • ClamAV: Xls.Downloader.Emotet-b649c93692b4c9d9-9976616-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet-b649c93692b4c9d9-9976616-0
  • LOLBin token sequence in document text high SE_LOLBIN_RUN_COMMAND
    Extracted document text contains a Windows script/execution tool name (PowerShell, mshta, cmd, rundll32, regsvr32, …) within 220 characters of a dangerous flag, command verb, or URL. This is a visible 'run this' instruction in HTML/PDF/RTF lure bodies, or — in macro-laden Office files — the macro's own string-pool entries appearing adjacent in extracted text.
  • Excel 4.0 (XLM) macro sheet present medium OLE_XLM_AUTOOPEN
    Workbook contains an Excel 4.0 macro sheet sub-stream — XLM is rarely seen in modern legitimate workbooks and was a major Office malware vector during 2020-2022.
  • 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.
  • 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://ftp.agir-santeinternationale.com/doctors/KAacngW97n4ApzVBDdGy/
    • http://www.vinyz.com/admin3693/BDFFgAZ6zBRumcUSG/
    • http://ly.yjlianyi.top/wp-admin/NRAdJ/
    • http://www.muyehuayi.com/cmp/Vtm2m7z88g/

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
092cde94571581ea266d3d2b6052a5540aa5ac9d587e4d72ed7e56a75331a843		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 9193 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 4 shell/COM execution token(s).

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