Malicious Office (OLE) / .RB0 — malware analysis report

Static analysis result for SHA-256 7247b9e0e54bfa15…

MALICIOUS

Office (OLE) / .RB0

138.5 KB Created: 2006-07-06 07:08:13 Authoring application: Microsoft Excel
MD5: 719e3bb24762708c329ed150cf4601cc SHA-1: 0ab4694907d8a886a7953c5ea28accadf35ea355 SHA-256: 7247b9e0e54bfa15cc8e2d4296186d08c24a17bcdd0633c6d2ccb56979e1fadd
88 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The OLE document contains VBA macros that are configured to execute automatically upon opening the workbook. The heuristic 'OLE_VBA_PCODE_AUTOEXEC_EXEC' specifically indicates that a 'Shell' execution token is present, suggesting the macro attempts to run an external command. While the VBA code itself is minimal and does not contain explicit download or execution logic, the presence of an auto-executing shell command is highly suspicious and indicative of a malicious macro-based document, likely delivered via spearphishing.

Heuristics 3

  • OLE document has large unaccounted-for region high OLE_SLACK_ANOMALY
    OLE file is 141,824 bytes but its declared streams total only 83,960 bytes — 57,864 bytes (41%) 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).
  • 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 contains no executable statements low OLE_VBA_MACROS
    Document contains a VBA project, but extracted modules only contain attributes/options/comments and no executable statements.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
7f506327609c082af1cd37dde23bc2c71a000f7d1ef530b6abb66775040a7673
vba-macro oletools.olevba.extract_macros (decoded VBA source) 1206 bytes