Office (OOXML) malware analysis — malicious · aa55e28506b1cf2b

MALICIOUS

Office (OOXML)

18.2 KB Created: 2021-07-08 15:10:44 UTC Authoring application: Microsoft Excel 16.0300

MD5: e61aeb28e8466b9c18822f14abe0a6e5 SHA-1: e4921c20d5ae12c18ef29ebe226829f58f38aedd SHA-256: aa55e28506b1cf2bf0d067ff7625b00e02fa71d842fe3409544c2d31a8d26b45

322 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1059 Command and Scripting Interpreter T1204.002 Malicious File T1566.001 Spearphishing Attachment

The file is an Office document containing a Workbook_Open VBA macro, a common technique for initial execution. The macro uses WScript.Shell and CreateObject to execute obfuscated code, which is designed to download and run a second-stage payload. The obfuscated nature and the use of auto-execution routines suggest a downloader or droppper malware.

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` `e51d097ff399ccdb80a67ca3f8fa37ecbe6d8358e436bfc61dcb91b2f0053883`	vba-macro	oletools.olevba.extract_macros (decoded VBA source from OOXML)	7072 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 9 long base64-like blob(s).
`vbaProject_00.bin` `082e094bedbd8aaa4fcc67fd3ecf8c5478c9b8ebe224f88de71786ed82efdbfa`	vba-project	OOXML VBA project: xl/vbaProject.bin	24576 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 9 long base64-like blob(s).

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