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

Static analysis result for SHA-256 06cca99c7276b090…

MALICIOUS

Office (OOXML) / .XLSX

66.4 KB Created: 2021-04-01 02:59:13 UTC Authoring application: Microsoft Excel 16.0300
MD5: 737f89da37437a70062111ad8ad73e66 SHA-1: 5ea2e0c8c4be4316f6b3c6fdb726712eb544173e SHA-256: 06cca99c7276b0900994160df03abf629a26a97f73da9e327ea775d19d7bb305
322 Risk Score

Malware Insights

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

The file is an Excel document containing obfuscated VBA macros that execute upon opening. The macros are designed to download and execute a second-stage payload, as indicated by the 'OLE_VBA_OBFUSCATED_AUTOEXEC_LOADER' and 'OLE_VBA_PCODE_AUTOEXEC_EXEC' heuristics. ClamAV detection further confirms its malicious nature, identifying it as 'Doc.Dropper.Onico-6152249-0'.

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: Doc.Dropper.Onico-6152249-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Dropper.Onico-6152249-0
  • 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.
  • Workbook_Open macro high OLE_VBA_WBOPEN
    Workbook_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://ns.adobe.com/xap/1.0/
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#
    • http://purl.org/dc/elements/1.1/

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
ab037236ec68bfd4dffbf7ee5fff4dc9dba05c5f05caded058bfdbacb257b5ef		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 2581 bytes
vbaProject_00.bin
df3f991a5611ea136d83d692b4014243b79826a1a6f719dd8b4a64c5f0ca207b		 vba-project OOXML VBA project: xl/vbaProject.bin 15872 bytes
Detection
ClamAV: Doc.Dropper.Onico-6152249-0
Obfuscation or payload: unlikely

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