Office (OOXML) / .XLSX malware analysis — malicious · 88671a5d96d0741f

MALICIOUS

Office (OOXML) / .XLSX

435.1 KB Created: 2021-08-19 14:03:52 UTC Authoring application: Microsoft Excel 16.0300

MD5: adfcfa59a06bbc5a0faa8f5b0ff663fe SHA-1: 01d4b8e70b641863727d671e9b087633f3b3a37e SHA-256: 88671a5d96d0741f41a8fab45db69ba8331ab55d6cc3fe0077ea3d7f30d82d39

320 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1059.003 Windows Command Shell T1204.002 Malicious File T1105 Ingress Tool Transfer

The file is an Excel spreadsheet containing a Workbook_Open macro, which is a common technique for executing malicious code upon opening. The macro utilizes WScript.Shell and CreateObject to execute an obfuscated Shell command that includes a URL, strongly indicating an attempt to download and execute a second-stage payload. The presence of a 'macros.bas' file further supports the macro-based execution.

Heuristics 7

Shell() call in VBA critical OLE_VBA_SHELL

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

WScript.Shell usage
Obfuscated VBA Shell command with URL critical OLE_VBA_OBFUSCATED_SHELL_URL

VBA macro invokes Shell with command text assembled through decoder or string-manipulation functions and includes a URL. This is a high-confidence downloader/dropper pattern, stronger than Shell or URL evidence on their own.
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` `cfeeabf24d676ed093c69130e3e85df0fa971f66a9aa628a1740ca846d5c28df`	vba-macro	oletools.olevba.extract_macros (decoded VBA source from OOXML)	1278 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 shell/COM execution token(s). Carved macro source contains an auto-exec entry point and execution/download terms.
`vbaProject_00.bin` `8ac32a052ad2fa886dccb4449252d78c27b174e749a0b778325bc9a136fd7efe`	vba-project	OOXML VBA project: xl/vbaProject.bin	4608 bytes

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