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

Static analysis result for SHA-256 737b82f5b99409ca…

MALICIOUS

Office (OLE) / .A

80.1 KB Created: 2000-08-09 13:36:00 Authoring application: Microsoft Word 8.0
MD5: 610b369c871bcf14e58eb2126a4055c4 SHA-1: f6d3d988fdd00a7756c30d15b027a72270a905b2 SHA-256: 737b82f5b99409ca662380ec6b5d1896151d514091170e76622a035708c851bf
420 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment T1082 System Information Discovery T1204.002 Malicious File

The sample is a malicious Office document containing VBA macros. The AutoOpen and AutoClose macros are present, and the critical OLE_VBA_SHELL heuristic indicates a Shell() call within the VBA code. This suggests the macro is designed to execute arbitrary commands, likely to download and run a second-stage payload. The presence of AutoOpen and AutoClose macros, along with the Shell() call, strongly points towards a macro-based downloader.

Heuristics 11

  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • Reference to WinExec API high SC_STR_WINEXEC
    Reference to WinExec API
  • Reference to ShellExecute API high SC_STR_SHELLEXEC
    Reference to ShellExecute API
  • Reference to LoadLibrary API high SC_STR_LOADLIBRARY
    Reference to LoadLibrary API
  • Reference to GetProcAddress API high SC_STR_GETPROCADDRESS
    Reference to GetProcAddress API
  • OLE document has large unaccounted-for region high OLE_SLACK_ANOMALY
    OLE file is 82,008 bytes but its declared streams total only 33,219 bytes — 48,789 bytes (59%) live in unallocated sector slack. This is the canonical hiding place for pre-macro-era Office exploit payloads (XOR-encoded shellcode reached via a parser pointer-corruption bug in the document structure).
  • AutoOpen macro high OLE_VBA_AUTOOPEN
    AutoOpen macro
  • Auto_Close macro high OLE_VBA_AUTOCLOSE
    Auto_Close macro
  • 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.
  • Reference to VirtualAlloc API medium SC_STR_VIRTUALALLOC
    Reference to VirtualAlloc API
  • 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
9130e430761a2b17f80edfde83e804e5949af6fdc607a39af8a18c0f1b3694c8		 vba-macro oletools.olevba.extract_macros (decoded VBA source) 4181 bytes

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