MALICIOUS
298
Risk Score
Malware Insights
MITRE ATT&CK
T1059.001 PowerShell
T1204.002 Malicious File
The sample is identified as a malicious PDF dropper by ClamAV. Static analysis reveals critical findings related to XFA forms and JavaScript, specifically indicating a heap-spray exploit. The embedded JavaScript, identified as 'stream_000_off00000049.js', is highly suspicious and likely responsible for initiating the exploit chain. The presence of a polyglot child PDF further suggests a multi-stage attack. The primary function appears to be the execution of an embedded script payload, which is characteristic of malware designed to download and execute further stages.
Heuristics 9
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XFA form contains risky executable script high PDF_XFA_SCRIPTPDF embeds an XFA form whose script block contains exploit, submission/launch, or shell-execution primitives. Ordinary LiveCycle print/update scripts are left as generic XFA/JS signals unless stronger behavior is present.
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Secondary embedded PDF body has suspicious static findings critical POLYGLOT_CHILD_PDF_STATIC_TRIAGEA valid PDF body was found at a nonzero offset inside another container and its carved contents matched PDF exploit or lure heuristics. This catches polyglots where the top-level magic routes to ZIP/OLE while a PDF reader or downstream parser opens the hidden PDF payload.
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XFA JavaScript heap-spray exploit code critical PDF_XFA_HEAP_SPRAYPDF contains XFA script content with heap-spray or shellcode-like JavaScript markers such as large encoded word sequences, util.pack, large arrays, or spray variable names. This is a weaponised Adobe Reader exploit pattern, not a normal interactive form.
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ClamAV: Pdf.Dropper.Agent-7280353-0 critical CLAMAV_DETECTIONClamAV detected this file as malware: Pdf.Dropper.Agent-7280353-0
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OLE document has large unaccounted-for region high OLE_SLACK_ANOMALYOLE file is 405,508 bytes but its declared streams total only 0 bytes — 405,508 bytes (100%) 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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Embedded script payload in PDF stream medium PDF_EMBEDDED_SCRIPT_PAYLOADPDF stream bytes contain an HTML/XFA <script> tag without accompanying Windows shell-execution primitives — common in accessible XFA forms but worth surfacing for analyst review.
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XFA form low PDF_XFAPDF uses XML Forms Architecture — can contain script logic
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String.fromCharCode low PDF_FROMCHARCODEString.fromCharCode found — used to construct payload strings dynamically. Common in benign JavaScript libraries for codepoint manipulation, so this alone is informational; weaponised use is also caught by the dedicated fromCharCode-stage and exploit-shape rules. (matched inside decoded stream)
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Suspicious extracted artifact info EXTRACTED_FILE_STATIC_TRIAGEOne or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.
Extracted artifacts 2
Files carved from inside the sample during analysis.
| Filename | Kind | Source | Size |
|---|---|---|---|
stream_000_off00000049.js0372351f0cb4c23e2ed02ac76db367f727b4464fc4d8fed4166853716cbd9c4f |
decompressed-pdf-stream | PDF FlateDecoded stream at offset 0x49 | 4194304 bytes |
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Detection
ClamAV:
No threats found
Obfuscation or payload:
likely
Carved artifact contains 4 eval/decoder/string-building token(s).
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polyglot_child_pdf_off000003e8.pdf3f8a341a7ae3492906bd80b80e4ae12887a15dd5f81f7fb9c6369e92129f7758 |
polyglot-child-pdf | Secondary PDF body inside ole container at offset 0x3E8 | 404508 bytes |
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