Office (OOXML) malware analysis — malicious · 22a1d1dbd0f7d03e

MALICIOUS

Office (OOXML)

19.6 KB Created: 2021-07-28 16:09:27 UTC Authoring application: Microsoft Excel 16.0300

MD5: 8dd4e12b5e4d2cfba8dabadc73adb7e9 SHA-1: 1e3c014c77b28b73f30d0319ba701bb6a0bfb661 SHA-256: 22a1d1dbd0f7d03e9f2539b5001d815e86ef585cb94422cf96c05ba25a2cb456

322 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1218.011 Signed Binary Proxy Execution: Rundll32

The file is an Excel document containing a Workbook_Open macro, a common technique for initiating malicious execution. The macro utilizes WScript.Shell and CreateObject to execute obfuscated VBA code, which likely decodes and launches a second-stage payload. The presence of 'Shell()' and 'WScript.Shell' firings strongly indicates an attempt to run external commands or scripts.

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` `1342f111a4a963cd6ea43edffe9450c4705a1bef0b6fd70c8f0ac711f53711f9`	vba-macro	oletools.olevba.extract_macros (decoded VBA source from OOXML)	8084 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 10 long base64-like blob(s).
`vbaProject_00.bin` `1a0796c06f62c043183b37df7e983cadd553dec4e5927020c9981afd19503ef6`	vba-project	OOXML VBA project: xl/vbaProject.bin	27136 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 10 long base64-like blob(s).

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