Malicious Office (OLE) / .XLSX — malware analysis report

Static analysis result for SHA-256 4b4bcdcc293f734c…

MALICIOUS

Office (OLE) / .XLSX

530.0 KB Created: 2022-02-15 14:47:03 Authoring application: Microsoft Excel First seen: 2022-03-09
MD5: b21053de4824f2d8197cf3deebbcb96f SHA-1: ad538c08df7228628f680302f548eecf6c5a2fa1 SHA-256: 4b4bcdcc293f734c7504ef54fbc90c4399210a0617a8f25e5c660d5735b1d7dd
380 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1059.003 Windows Command Shell T1547.001 Registry Run Keys / Startup Folder T1059.005 Visual Basic

The sample is an Excel file containing VBA macros, specifically an Auto_Open macro that executes code. The script uses WScript.Shell and cmd.exe to create a scheduled task named 'Windows Update' that downloads a file from 'https://srv1.aztronic.com.br/Atendimento_calper/imagens/seguroacesso.txt' and saves it as 'C:\users\public\downloads\seguro.zip'. It also creates a file 'C:\Users\Public\Downloads\avaliacao.txt' with commands for bitsadmin. The use of Auto_Open, WScript.Shell, cmd.exe, and schtasks indicates a downloader and execution pattern.

Heuristics 9

  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • WScript.Shell usage critical OLE_VBA_WSCRIPT
    WScript.Shell usage
  • Reference to Windows Script Host high SC_STR_WSCRIPT
    Reference to Windows Script Host
  • Auto_Open macro high OLE_VBA_AUTO
    Auto_Open macro
  • 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.
  • 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 macros detected medium OLE_VBA_MACROS
    Document contains VBA macro code

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
394f068f31fcc2a9e5bec8ece7dbf2c4e5939ad906aceccde5bcf88910f1230a		 vba-macro oletools.olevba.extract_macros (decoded VBA source) 5732 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 shell/COM execution token(s). Carved macro source contains an auto-exec entry point and execution/download terms.

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