Malicious Office (OOXML) / .XLSM — malware analysis report

Static analysis result for SHA-256 f0628b1d7443ba3a…

MALICIOUS

Office (OOXML) / .XLSM

398.2 KB First seen: 2022-08-20
MD5: 5db2d06e8d32b5965ed0a9305582aeca SHA-1: 58bec9c67f37b606d6539b7119862f7f335e79f3 SHA-256: f0628b1d7443ba3a68bf872dd442ce3e71636c3d180a17292e221d55fa050af2
322 Risk Score

Malware Insights

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

The Workbook_Open macro is obfuscated and uses CreateObject to execute a PowerShell command. This PowerShell command downloads a file named 'v.exe' from 'http://visitor-v.dd-dns.de/v.exe' and saves it as 'ytmnq.exe' in the public user directory, then executes it. This indicates a downloader or dropper functionality.

Heuristics 8

  • Obfuscated auto-exec VBA loader critical OLE_VBA_OBFUSCATED_AUTOEXEC_LOADER
    Auto-exec VBA reconstructs strings with a heavy custom decoder (numeric char-array, repeated hex-string decode, or junk-token Replace removal) and feeds them to a COM-instantiation or execution sink. This obfuscated-loader shape keeps CreateObject/Shell/URL indicators out of the macro source.
  • ClamAV: Xls.Dropper.EPPlus-9802867-2 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Dropper.EPPlus-9802867-2
  • ClamAV detection on extracted artifact critical EXTRACTED_FILE_CLAMAV
    ClamAV flagged at least one file extracted from inside this sample. Even when the wrapping document carries no AV detection of its own, a hit on the carved artifact is a strong indicator the sample is a delivery vehicle.
  • Workbook_Open macro high OLE_VBA_WBOPEN
    Workbook_Open macro
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
  • 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.
  • VBA project inside OOXML medium OOXML_VBA
    Document contains a VBA project — VBA macros present
  • 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://visitor-v.dd-dns.de/v.exe

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
552ce7e6cc48e61e2074c3f6b06bf64ad6af9b18d9cb074b6dcbfde0ccaa59b4		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 1630 bytes
vbaProject_00.bin
562bf9af75f3d92d92706260d63b3f8e3ab7da1e3c0b338edef723bdf0794176		 vba-project OOXML VBA project: xl/vbaProject.bin 5120 bytes
Detection
ClamAV: Xls.Dropper.EPPlus-9802867-2
Obfuscation or payload: unlikely

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