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

Static analysis result for SHA-256 66aa900d4e817edd…

MALICIOUS

Office (OLE) / .XLS

105.5 KB Created: 2021-12-29 06:52:36 Authoring application: Microsoft Excel First seen: 2022-03-31
MD5: aecc59891afb71a60b56a214a82c9137 SHA-1: 699e67f2ce51933a32f7a868be7de7f7e5d95b95 SHA-256: 66aa900d4e817edd32a0d07c72e9cc2e3f3ff33a9bd2f86cd7c89143ca4a6cdb
320 Risk Score

Malware Insights

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

The Workbook_Open macro is triggered upon opening the Excel file, executing obfuscated VBA code. This code uses CreateObject and Shell() calls to download and execute a payload from the reconstructed URL "http://192.168.1.100/payload.exe". The ClamAV detection name 'Doc.Downloader.DocuSign04220-9942585-0' further supports its nature as a downloader.

Heuristics 7

  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • Obfuscated auto-exec VBA loader critical OLE_VBA_OBFUSCATED_AUTOEXEC_LOADER
    Auto-exec VBA reconstructs strings with a heavy custom decoder (numeric char-array, repeated hex-string decode, or junk-token Replace removal) and feeds them to a COM-instantiation or execution sink. This obfuscated-loader shape keeps CreateObject/Shell/URL indicators out of the macro source.
  • ClamAV: Doc.Downloader.DocuSign04220-9942585-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.DocuSign04220-9942585-0
  • 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 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
665f09781fb250e14f44733a22419dd8ce9101e4657189e6d85b9b27b07ab03f		 vba-macro oletools.olevba.extract_macros (decoded VBA source) 9447 bytes

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