Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 0b0ff167a2abc391…

MALICIOUS

Office (OLE) / .XLSX

218.0 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel First seen: 2023-02-11
MD5: c0142b09ee6bdeded8a78e1118ad1b24 SHA-1: 3c5f6dddade6670758f2b2b9bfa55aafeb0d86c3 SHA-256: 0b0ff167a2abc391dff0d8277e2a22d32761a19950d161a9a7e6883df152b6c1
322 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Service Execution: Visual Basic T1204.002 Malicious File Execution: Malicious File T1059.001 Command and Scripting Interpreter: PowerShell T1059.003 Command and Scripting Interpreter: Windows Command Shell

The file contains Excel 4.0 macros, including an Auto_Open entry, which is a known technique for executing malicious code. The macros utilize the URLDownloadToFile API to download a payload from one of the embedded URLs. The presence of 'regsvr32.exe' in the document text further suggests the execution of downloaded content. ClamAV detection confirms this as Emotet.

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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