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

Static analysis result for SHA-256 879128e97be4b92c…

MALICIOUS

Office (OOXML) / .XLSM

139.4 KB Created: 2020-07-05 11:00:55 UTC Authoring application: Microsoft Excel 16.0300
MD5: a1a069dfb1da1cddc32d34603f827fcf SHA-1: 81fe8842dc0f7596fe8e7bba32f1e81e261cee30 SHA-256: 879128e97be4b92c1ce5b1017b320d8884a22ff66694716c0efb66a64f9d407b
382 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File

The XLSM file contains a Workbook_Open macro that utilizes Wscript.Shell to execute obfuscated code. This code decodes a string, likely a command or URL, which is then executed. The ClamAV detection 'Xls.Downloader.Obfuse-9382072-0' further indicates a downloader functionality. The primary technique observed is the use of Visual Basic for Application (VBA) to execute arbitrary code.

Heuristics 9

  • 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
  • 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
  • Suspicious extracted artifact info 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.

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
9c8774b08fd394ba96bfa6d6c436691f804436ff63d4c00d16940148f71a2796		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 1589 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 long base64-like blob(s).
vbaProject_00.bin
9d57c6f9470ece4297739920f566b23fd18912f1c61d1a39e4915790919ffe9f		 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 long base64-like blob(s).

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