Office (OOXML) malware analysis — malicious · 06321f00942c19c8

MALICIOUS

Office (OOXML)

21.2 KB Created: 2021-08-20 14:59:43 UTC Authoring application: Microsoft Excel 16.0300

MD5: 426edf1c496d5ace15f46142c8e1128b SHA-1: 90b346ce14d5301e89f8c80eda72c5b21ba7fd2f SHA-256: 06321f00942c19c8e0dcbaec86ac17d55d84c9f60476582e479a72511a9d544c

384 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1204.002 Malicious File

The Excel file contains a Workbook_Open macro that utilizes WScript.Shell and CreateObject to execute obfuscated VBA code. This code appears to be a loader designed to download and execute a second-stage payload from an embedded URL. The obfuscation and use of Shell() calls are strong indicators of 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.

Filename	Kind	Source	Size
`macros.bas` `30b6babd04b7ddd7e5d895223d6067b097b3cb93633e64b03b88398d9778eb34`	vba-macro	oletools.olevba.extract_macros (decoded VBA source from OOXML)	9316 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 9 long base64-like blob(s).
`vbaProject_00.bin` `1c3579dfcf5fc4fb98be707cce4c67f728f43c7e1214c806be5672a01832ab8d`	vba-project	OOXML VBA project: xl/vbaProject.bin	30208 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 9 long base64-like blob(s).

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