Office (OOXML) malware analysis — malicious · 05d269db6e8e0289

MALICIOUS

Office (OOXML)

21.6 KB Created: 2021-08-19 15:05:44 UTC Authoring application: Microsoft Excel 16.0300

MD5: 9eefb55feaf9bb6c1bfa8a64c942b3d7 SHA-1: 5d711e464c2b210520182e8688ada466f4d1c129 SHA-256: 05d269db6e8e0289a545ff6f9d6c5a791dca169e37dbd37c4d7e9f0b37f69521

384 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1204.002 Malicious File

The file contains a Workbook_Open macro that utilizes WScript.Shell and CreateObject to execute obfuscated VBA code. This code appears to be designed to download and execute a second-stage payload from the embedded URL, 'https://brightcarbon.com/'. The use of obfuscation and the auto-execution nature of the macro indicate a malicious intent to compromise the user's system.

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.

Filename	Kind	Source	Size
`macros.bas` `0803d3651873206a37344b1e30781e92e9792a6094d9562ec730ed23690fe801`	vba-macro	oletools.olevba.extract_macros (decoded VBA source from OOXML)	9614 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 9 long base64-like blob(s).
`vbaProject_00.bin` `704820bfadd7abaf6abc5cdaacaad13ba6fbb54ef18ae108e9ea5fc452682fa8`	vba-project	OOXML VBA project: xl/vbaProject.bin	30720 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 9 long base64-like blob(s).

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