Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 84c1b6907ae7bdb6…

MALICIOUS

Office (OOXML)

20.9 KB Created: 2021-08-20 14:59:00 UTC Authoring application: Microsoft Excel 16.0300
MD5: 39c4cb3052a8ec3289f4a5a565fc8a7a SHA-1: 3a2623eace48dfd41025540aa0a3a460061df3c5 SHA-256: 84c1b6907ae7bdb67f4d9a7e4d7868f87a1b0ec7c72c670a20cfc42b61659fdf
384 Risk Score

Malware Insights

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

The sample is a macro-enabled Excel document containing a Workbook_Open macro that utilizes WScript.Shell and CreateObject to execute obfuscated VBA code. This code appears to download and execute a second-stage payload from the embedded URL. The obfuscation and use of auto-executing macros indicate malicious intent.

Heuristics 10

  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • WScript.Shell usage critical OLE_VBA_WSCRIPT
    WScript.Shell usage
  • 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.
  • 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.
  • 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
  • Suspicious extracted artifact info 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.
  • 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 https://brightcarbon.com/

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
267c27ae144df18940859209ab4f0b61e7f38147305f0f8052e0f5fbdc7c2b1d		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 10320 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 10 long base64-like blob(s).
vbaProject_00.bin
633e65d0f5e275312e32f34110c3e98e88f390bb7a78783ec9308a9bfc05a5d1		 vba-project OOXML VBA project: xl/vbaProject.bin 31232 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 10 long base64-like blob(s).

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