Office (OOXML) / .XLSX malware analysis — malicious · 40902a40b1d1abd6

MALICIOUS

Office (OOXML) / .XLSX

20.5 KB Created: 2021-08-11 00:23:11 UTC Authoring application: Microsoft Excel 15.0300

MD5: 49be70c935e80f0e61debd1ca5b8f87f SHA-1: 6d6964955d1c4e620e79e48c69e292f18c2402a6 SHA-256: 40902a40b1d1abd6e6b7a2d4c463d454e92eaecb3a7518d046754ffd269f217a

260 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1059.001 PowerShell T1204.002 Malicious File

The presence of a Workbook_Open macro, along with critical firings for Shell() and WScript.Shell usage, strongly indicates that this XLSX file is designed to execute arbitrary code upon opening. The VBA script is heavily obfuscated and truncated, but the structure suggests it attempts to download and execute a secondary payload. Due to the obfuscation and lack of clear IOCs in the provided script excerpt, the exact family cannot be determined.

Heuristics 6

Shell() call in VBA critical OLE_VBA_SHELL

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

WScript.Shell usage
Workbook_Open macro high OLE_VBA_WBOPEN

Workbook_Open macro
CreateObject call high OLE_VBA_CREATEOBJ

CreateObject call
Suspicious extracted artifact high 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.
VBA project inside OOXML medium OOXML_VBA

Document contains vbaProject.bin — VBA macros present

Extracted artifacts 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`macros.bas` `b13a4e51139eae89a2b78fcaaaef0c8d9cea0531ee576dabd3a40095632ed9de`	vba-macro	oletools.olevba.extract_macros (decoded VBA source from OOXML)	9012 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 shell/COM execution token(s). Carved artifact contains 8 long base64-like blob(s). Carved macro source contains an auto-exec entry point and execution/download terms.
`vbaProject_00.bin` `0079f34d031729c6fdfe254f1ccdcb81ebffdc476df0ce42d20c9a891eb4e0b0`	vba-project	OOXML VBA project: xl/vbaProject.bin	29696 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 shell/COM execution token(s). Carved artifact contains 8 long base64-like blob(s). Carved macro source contains an auto-exec entry point and execution/download terms.

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