Malicious Office (OOXML) / .XLSM — malware analysis report

Static analysis result for SHA-256 85d81b6f9a9ec977…

MALICIOUS

Office (OOXML) / .XLSM

27.3 KB Created: 2021-08-19 14:03:52 UTC Authoring application: Microsoft Excel 15.0300
MD5: 773c7adad111dacf5eab1061c9f254cb SHA-1: 90401b587834daf8e0306b3b4a2808afe1825df1 SHA-256: 85d81b6f9a9ec97701b96279ed76f478e6c528fa999c2c62afa883afd35146e5
342 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution T1105 Ingress Tool Transfer

The sample is a macro-enabled Excel file (XLSM) containing a Workbook_Open macro. This macro executes a command using cmd.exe to download a file from http://trietlongvinhvien.info//.tmb/ID4/4rodtz.exe using certutil and then executes the downloaded file. This indicates a downloader or dropper functionality.

Heuristics 8

  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • LOLBin reference in VBA critical OLE_VBA_LOLBIN
    LOLBin reference in VBA
  • ClamAV: Xls.Dropper.EPPlus-9802867-2 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Dropper.EPPlus-9802867-2
  • 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
  • cmd.exe reference in VBA high OLE_VBA_CMD
    cmd.exe reference in VBA
  • VBA project inside OOXML medium OOXML_VBA
    Document contains a VBA project — VBA macros present
  • 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://trietlongvinhvien.info//.tmb/ID4/4rodtz.exe

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
7918079fce3cdc156245650b3d5e95182b3ed8343784f94838389b9e7ead581d		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 1133 bytes
vbaProject_00.bin
bb7cbd09484455ec3287e6745e01c8863f681baecf7517805845ceb8c894b54b		 vba-project OOXML VBA project: xl/vbaProject.bin 5632 bytes
Detection
ClamAV: Xls.Dropper.EPPlus-9802867-2
Obfuscation or payload: unlikely

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