Office (OOXML) malware analysis — malicious · 5b16f5508778d8b7

MALICIOUS

Office (OOXML)

19.0 KB Created: 2021-07-30 14:35:15 UTC Authoring application: Microsoft Excel 16.0300

MD5: fb910b8e640374c86e00243684478d40 SHA-1: 688a7cd13aa45d3be6fed1b0d88c55463928484e SHA-256: 5b16f5508778d8b75ca3ebea056fb168fb872e4d6f6b9a5af514053d7c9ea57f

322 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1204.002 Malicious File

The sample is an Office document containing a Workbook_Open macro that executes obfuscated VBA code. This code utilizes WScript.Shell and CreateObject to likely download and execute a second-stage payload. The obfuscated nature and use of auto-execution routines suggest a downloader or droppper functionality.

Heuristics 8

Shell() call in VBA critical OLE_VBA_SHELL

Shell() call in VBA
WScript.Shell usage critical OLE_VBA_WSCRIPT

WScript.Shell usage
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.

Extracted artifacts 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`macros.bas` `ffcadb7ab2445fc4025978b1096643e35b6d55aa379aca57b1f1bc930be17221`	vba-macro	oletools.olevba.extract_macros (decoded VBA source from OOXML)	7302 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 9 long base64-like blob(s).
`vbaProject_00.bin` `a10ab8f1de7afbf0006f118f8ba71c39e170a042195b37866d008bc973771cce`	vba-project	OOXML VBA project: xl/vbaProject.bin	26112 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 9 long base64-like blob(s).

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