Office (OOXML) / .XLSM malware analysis — malicious · b2741e8b5c4518f8

MALICIOUS

Office (OOXML) / .XLSM

139.4 KB Created: 2020-07-04 14:15:47 UTC Authoring application: Microsoft Excel 16.0300

MD5: 3d9bf8945b2539d305eec73f1fb7dda8 SHA-1: ffee1cc6a3af48139301f2c387a3244c4641c634 SHA-256: b2741e8b5c4518f8eefe156dd494c2f791ce6f4b5fda13f37f79b98442839377

380 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1059.003 Windows Command Shell T1204.002 Malicious File

The file is an XLSM document containing VBA macros. A critical heuristic firing indicates the presence of a Workbook_Open macro, which is designed to execute automatically when the document is opened. This macro utilizes WScript.Shell and CreateObject to execute commands, likely downloading and running a secondary payload. ClamAV signatures confirm this behavior, identifying it as a downloader.

Heuristics 8

Shell() call in VBA critical OLE_VBA_SHELL

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

WScript.Shell usage
ClamAV: Xls.Downloader.Obfuse-9382072-0 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Xls.Downloader.Obfuse-9382072-0
ClamAV detection on extracted artifact critical EXTRACTED_FILE_CLAMAV

ClamAV flagged at least one file extracted from inside this sample. Even when the wrapping document carries no AV detection of its own, a hit on the carved artifact is a strong indicator the sample is a delivery vehicle.
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` `9e8a402ad299696a08fcf115e4e1dc16fe58c29e0e94d21f6ce080a790d1e57c`	vba-macro	oletools.olevba.extract_macros (decoded VBA source from OOXML)	1591 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 shell/COM execution token(s). Carved artifact contains 1 long base64-like blob(s). Carved macro source contains an auto-exec entry point and execution/download terms.
`vbaProject_00.bin` `a0ffd965e7ccf97703d82cad9eac30d81cb9b04ecde3dc4485cc9a071987ac31`	vba-project	OOXML VBA project: xl/vbaProject.bin	14848 bytes
Detection ClamAV: Xls.Downloader.Obfuse-9382072-0 Obfuscation or payload: likely Carved artifact contains 1 shell/COM execution token(s). Carved artifact contains 1 long base64-like blob(s). Carved macro source contains an auto-exec entry point and execution/download terms.

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