Office (OOXML) / .XLSX malware analysis — malicious · 3bbae53fc0044916

MALICIOUS

Office (OOXML) / .XLSX

324.5 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 16.0300

MD5: 6856ae442ed396ac95413e4b9539f7b7 SHA-1: f707f78fe02a3bc0a01b36f23cf1b96d7c2461f7 SHA-256: 3bbae53fc00449166fd9255b3f3192deba0b81b41b6e173d454c398a857b5094

150 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1059.001 PowerShell T1140 Deobfuscate/Decode Files or Information T1036 Masquerading

The sample contains a Workbook_Open VBA macro, which is a common technique for executing malicious code upon opening an Office document. The macro obfuscates binary data using string concatenation and writes it to a file named 'WindowsSecurity.zip' within the user's AppData directory. It also uses GetObject to interact with the file system and environment variables, suggesting it aims to download and execute a secondary payload. The obfuscation and use of common Windows directories point towards a downloader or droppper functionality.

Heuristics 6

Workbook_Open macro high OLE_VBA_WBOPEN

Workbook_Open macro
GetObject call high OLE_VBA_GETOBJ

GetObject 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
Environ() call (env variable access) low OLE_VBA_ENVIRON

Environ() call (env variable access)
Embedded URL info EMBEDDED_URL

One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
URL http://schemas.openxmlformats.org/spreadsheetml/2006/main
- http://schemas.openxmlformats.org/officeDocument/2006/relationships
- http://schemas.openxmlformats.org/markup-compatibility/2006
- http://schemas.microsoft.com/office/spreadsheetml/2009/9/ac
- http://schemas.microsoft.com/office/spreadsheetml/2014/revision
- http://schemas.microsoft.com/office/spreadsheetml/2015/revision2
- http://schemas.microsoft.com/office/spreadsheetml/2016/revision3

Extracted artifacts 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`macros.bas` `03e843665d7a2844d78a89a2dc85f1a633b1b91a8c73c5ed890e5b176feed352`	vba-macro	oletools.olevba.extract_macros (decoded VBA source from OOXML)	5496 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 221 Chr/ChrW string-construction calls. Carved macro source contains an auto-exec entry point and execution/download terms.
`vbaProject_00.bin` `ea920732293f3564f7c726c4a88ac7dfa452e12a0e8fc6499e9c2d79bfe89ca0`	vba-project	OOXML VBA project: xl/vbaProject.bin	775168 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved macro source contains an auto-exec entry point and execution/download terms.

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