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

Static analysis result for SHA-256 62ddbea00d9daf68…

MALICIOUS

Office (OLE) / .XLSX

461.5 KB Created: 2015-06-05 18:17:20 Authoring application: Microsoft Excel
MD5: 42b43b6c4301d81b450ce98f16d5b100 SHA-1: db4cd94c17f26c867b747024b0ef5c95a2b7ee5e SHA-256: 62ddbea00d9daf68f52b3f5746c5e900d5dfe7e4792d5333557527d027e8d85d
220 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1059.005 Visual Basic T1203 Exploitation for Client Execution

The sample is an Excel file containing Excel 4.0 (XLM) macros, including an Auto_Open macro. The document body presents a social engineering lure, instructing the user to "Enable Editing" and "Enable Content" to view the document. The presence of an Auto_Open macro and the environment evasion techniques suggest the macro is designed to execute a malicious payload upon opening.

Heuristics 5

  • Excel 4.0 Auto_Open defined name critical OLE_XLM_AUTOOPEN_DEFINEDNAME
    oletools recovered an Auto_Open / Auto_Close entry from an Excel 4.0 macro sheet. The raw BIFF name can be tokenized or partially opaque to byte-string checks, but the recovered macro listing confirms the workbook has an XLM auto-execution entry.
  • XLM Auto_Open with dangerous formula APIs critical OLE_XLM_DANGEROUS_FN
    Excel 4.0 macro sheet contains an Auto_Open / Auto_Close entry and dangerous XLM formula APIs that can invoke programs, write files, or transfer control without VBA.
  • OLE document has large unaccounted-for region high OLE_SLACK_ANOMALY
    OLE file is 472,576 bytes but its declared streams total only 237,208 bytes — 235,368 bytes (50%) 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).
  • XLM Auto_Open environment-evasion HALT gate high OLE_XLM_ENVIRONMENT_EVASION_HALT
    Excel 4.0 macro sheet auto-executes multiple GET.WORKSPACE / GET.WINDOW environment checks and halts execution when the host does not match the expected user environment. This is a common sandbox-evasion pattern in XLM malware and is stronger than a bare XLM macro-sheet indicator.
  • Excel 4.0 (XLM) macro sheet present medium OLE_XLM_AUTOOPEN
    Workbook contains an Excel 4.0 macro sheet sub-stream — XLM is rarely seen in modern legitimate workbooks and was a major Office malware vector during 2020-2022.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
156f11803ebb8234de1ae358a2a4c093b9f4efdda51ef131d9e60e0417867675		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 335356 bytes

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