MALICIOUS
140
Risk Score
Malware Insights
MITRE ATT&CK
T1203 Exploitation for Client Execution
The file is identified as malicious due to critical heuristic firings indicating the exploitation of CVE-2009-3129, a known vulnerability in Microsoft Excel. This exploit likely allows for the execution of arbitrary code, potentially leading to the download and execution of a secondary payload. The large amount of slack space and appended payload bytes further support this conclusion.
Heuristics 3
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CVE-2009-3129 — Excel FEATHEADER record overflow critical CVE exact CVE_2009_3129Workbook BIFF stream contains a FEATHEADER (Feature Header) record with anomalous size (record_size=22, isf=4, cbHdrData=4). Legitimate FEATHEADER records are tiny (<100 bytes) and carry cbHdrData values that fit in the record body; the value here is the documented CVE-2009-3129 exploit primitive — cbHdrData drives a memcpy with attacker-controlled size, leading to memory corruption and code execution in Excel 2007/2003.
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OLE document has large unaccounted-for region high OLE_SLACK_ANOMALYOLE file is 332,433 bytes but its declared streams total only 24,565 bytes — 307,868 bytes (93%) 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).
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OLE file has appended executable-looking payload bytes high OLE_APPENDED_PAYLOADOLE compound file contains a large high-entropy region beyond the declared major streams and that region includes shellcode, PE, or loader API markers. This is a payload-carrier signal, not a specific CVE attribution by itself.
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