Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 1c0fe7a9e61c48d8…

MALICIOUS

Office (OOXML)

15.4 KB Created: 2021-07-21 13:28:07 UTC Authoring application: Microsoft Excel 16.0300
MD5: 087dfb65f09c8095784ef44a9713f274 SHA-1: 7b3ea3780d861b09f56a2c4bf47dc3b5be7736d0 SHA-256: 1c0fe7a9e61c48d88385a2aa12c91d79ba7dfa0e4614fb8e7c6858ee18b7887b
442 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1059.005 Visual Basic T1105 Ingress Tool Transfer

The Auto_Open macro directly executes a PowerShell command that downloads and runs a script from the URL http://85.31.217.41/a.bat. This PowerShell command is obfuscated within the VBA code, indicating a deliberate attempt to conceal its malicious activity. The extracted VBA code also contains a function that attempts to download files from a benign Cornell website, which may be a distraction or a secondary function.

Heuristics 10

  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • PowerShell reference in VBA critical OLE_VBA_PS
    PowerShell reference in VBA
  • Obfuscated VBA Shell command with URL critical OLE_VBA_OBFUSCATED_SHELL_URL
    VBA macro invokes Shell with command text assembled through decoder or string-manipulation functions and includes a URL. This is a high-confidence downloader/dropper pattern, stronger than Shell or URL evidence on their own.
  • ClamAV: Doc.Downloader.Generic-6680573-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.Generic-6680573-0
  • 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.
  • Auto_Open macro high OLE_VBA_AUTO
    Auto_Open macro
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
  • VBA p-code auto-exec with execution tokens high OLE_VBA_PCODE_AUTOEXEC_EXEC
    Compiled VBA/cache stream contains an auto-execution token together with shell/download/object-execution tokens. This catches p-code-only or source-extraction-failure macro documents where visible source is unavailable.
  • 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://85.31.217.41/a.bat
    • http://usda.mannlib.cornell.edu/MannUsda/viewDocumentInfo.do?documentID=1194
    • http://usda.mannlib.cornell.edu/MannUsda/viewDocumentInfo.do?documentID=1194�

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
d0d866195e7922c58464b5891d2c0d3b221624672d7fc737dbc9c14ed1c1109e		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 1684 bytes
vbaProject_00.bin
5169f082dc51759fbe086e4882138524c5ed7503e13513508e3ff37061ae68aa		 vba-project OOXML VBA project: xl/vbaProject.bin 18944 bytes
Detection
ClamAV: Doc.Downloader.Generic-6680573-0
Obfuscation or payload: unlikely

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