Office (OOXML) / .XLSX malware analysis — malicious · 7331846b7486706b

MALICIOUS

Office (OOXML) / .XLSX

17.6 KB Created: 2021-09-27 20:33:26 UTC Authoring application: Microsoft Excel 15.0300

MD5: dec66ca313a3724895c6da62d7f35024 SHA-1: ccfaba27f5b5b593a80fb4958da067aa59503e8d SHA-256: 7331846b7486706bb089a60a9885b54b37c432bf8bfc0de738573f0d2ceb487b

322 Risk Score

Malware Insights

MITRE ATT&CK

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

The file contains a Workbook_Open macro that triggers obfuscated VBA code. This code utilizes WScript.Shell and CreateObject to execute commands, indicating a downloader or initial execution stage. The obfuscated nature and use of WScript.Shell suggest a malicious intent to run further payloads.

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` `17aacb29bf38ba23ddd218099192cb6f6163ffb8f87134cbabe40b85681cb201`	vba-macro	oletools.olevba.extract_macros (decoded VBA source from OOXML)	6759 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 8 long base64-like blob(s).
`vbaProject_00.bin` `b13f960c278fd258ad3af5005709038b3c589142a47ff4683a7a2ca9e0dca8bb`	vba-project	OOXML VBA project: xl/vbaProject.bin	24064 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 8 long base64-like blob(s).

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