Office (OOXML) / .XLSM malware analysis — malicious · baf6c48bc6b148a2

MALICIOUS

Office (OOXML) / .XLSM

143.4 KB Created: 2020-06-17 16:05:19 UTC Authoring application: Microsoft Excel 16.0300

MD5: 8d3c1fd52a8b94c36e938158d2422b3a SHA-1: a783f9b3d55ea1331f1268682228ce3613a30cb0 SHA-256: baf6c48bc6b148a2da063d7b1557a4737f48ba6d2e8fc1ee944d6c288c45be3c

380 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 sample is a macro-enabled Excel file containing an Auto_Open macro that executes a Base64-decoded shell command. This command constructs a VBScript file at C:\ProgramData\poc.vbs which downloads an executable from https://manikmeyah.net/wp-cache/ty/yCiDC.exe. The VBScript then saves the downloaded file as Filename.exe in the user's temporary directory. This indicates a downloader or dropper functionality.

Heuristics 8

Shell() call in VBA critical OLE_VBA_SHELL

Shell() call in VBA
VBA Base64-decoded Shell command stager critical OLE_VBA_BASE64_SHELL_COMMAND_STAGER

VBA auto-exec macro decodes Base64 string literals into command or script-launch text and executes the result with Shell. This catches cmd/cscript/PowerShell/VBS launchers hidden from plain keyword matching.

URL https://manikmeyah.net/wp-cache/ty/yCiDC.exe
ClamAV: Xls.Dropper.Agent-8076741-0 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Xls.Dropper.Agent-8076741-0
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.
Auto_Open macro high OLE_VBA_AUTO

Auto_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` `7bd5c3ccadc259975627b12d28109ddede429a7ae1057ab8ff6e6ed06d232224`	vba-macro	oletools.olevba.extract_macros (decoded VBA source from OOXML)	3581 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 3 long base64-like blob(s). Carved macro source contains an auto-exec entry point and execution/download terms.
`vbaProject_00.bin` `5f8a587eb6697e24207b6f7c19161a5cf575038eaab88a0a5c454bd343db19b1`	vba-project	OOXML VBA project: xl/vbaProject.bin	20480 bytes
Detection ClamAV: Xls.Dropper.Agent-8076741-0 Obfuscation or payload: likely Carved artifact contains 4 long base64-like blob(s). Carved macro source contains an auto-exec entry point and execution/download terms.

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