Office (OOXML) malware analysis — malicious · df91813bbd9e0b09

MALICIOUS

Office (OOXML)

18.8 KB Created: 2021-07-28 16:05:30 UTC Authoring application: Microsoft Excel 16.0300

MD5: 82e0d48001000c3c291dc4bb9a3eaafe SHA-1: 8983411754f8e6dd903777734ae2589158d5f995 SHA-256: df91813bbd9e0b0910c16c9452cd91c03593fae3fba86810692211096e8c7fb2

322 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1204.002 Malicious File T1071.001 Web Protocols

The file contains a Workbook_Open macro that triggers obfuscated VBA code. This code utilizes WScript.Shell and CreateObject to execute commands, likely to download and run a second-stage payload. The presence of these critical heuristics indicates a malicious loader designed for further execution.

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` `69cec31c47b4a85b98ebab7f3c2a2d8bfacee17ac38ec50c6e7e72a3e4cacc28`	vba-macro	oletools.olevba.extract_macros (decoded VBA source from OOXML)	7208 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 9 long base64-like blob(s).
`vbaProject_00.bin` `85ea97636a7cc87840b49c3626062583754f2e655b5e3ee338ee22f659e4dd75`	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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