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

Static analysis result for SHA-256 08d30d6646117cd9…

MALICIOUS

Office (OLE) / .XLS

32.5 KB Created: 2022-04-14 18:51:43 Authoring application: Microsoft Excel First seen: 2022-04-15
MD5: 3aa6bf4ed8c485717d767013d43f7cdb SHA-1: 83ea9a8627819a7ba2ecad058f22e7f697256bc0 SHA-256: 08d30d6646117cd96320447042fb3857b4f82d80a92f31ee91b16044b87929c0
320 Risk Score

Malware Insights

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

The Workbook_Open macro is obfuscated and uses CreateObject and Shell() calls to download a DLL from "http://66.150.66.167/su.dll" and save it to "C:\Windows\Tasks\su.dll". It then attempts to execute the downloaded DLL using "rundll32 C:\Windows\Tasks\su.dll,PlugInInit". The use of obfuscated auto-execution and shell calls strongly indicates a downloader or dropper functionality.

Heuristics 7

  • 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.
  • 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.
  • 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
b72a409340ec150f137ea221d9022971b1ae137110f19423e0f27ddf051f8dc9		 vba-macro oletools.olevba.extract_macros (decoded VBA source) 1962 bytes

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