PDF malware analysis — malicious · 4311f981c6a3b598

MALICIOUS

PDF

1.95 MB Created: 2009-11-15 19:41:70 Authoring application: PDF Library 4.3.9 (via PDF Library 3.9.7)

MD5: 29753dca678c88645d96ab57452aa4e5 SHA-1: aa53f08e048656805a62786fe4815e735f9c4a8b SHA-256: 4311f981c6a3b5984bd94c0aa92e37ce68ff526190b44b55ef8315852184299d

262 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell T1204.002 Malicious File

The PDF file exhibits multiple high-severity heuristic firings related to JavaScript execution and obfuscation, including PDF_EVAL and PDF_FROMCHARCODE. The ML classifier also flagged it as malicious with high confidence. ClamAV detected the file as 'Win.Trojan.Agent-36166', and an extracted artifact also triggered ClamAV. The presence of embedded JavaScript streams, particularly one with significant size and obfuscation indicators, strongly suggests the intent to download and execute a second-stage payload.

Machine Learning

Nyx PDF Classifier malicious score 0.9998

Heuristics 10

ClamAV: Win.Trojan.Agent-36166 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Win.Trojan.Agent-36166
ClamAV detection on extracted artifact critical EXTRACTED_FILE_CLAMAV

ClamAV flagged at least one file extracted from inside this sample. Even when the wrapping document carries no AV detection of its own, a hit on the carved artifact is a strong indicator the sample is a delivery vehicle.
eval() call high PDF_EVAL

eval() found — commonly used for obfuscated exploit execution (matched inside decoded stream)
Secondary embedded PDF body has suspicious static findings high POLYGLOT_CHILD_PDF_STATIC_TRIAGE

A 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.
JavaScript action low PDF_JAVASCRIPT

PDF contains a /JavaScript action. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
Embedded JS stream low PDF_JS

PDF references a /JS stream. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
String.fromCharCode low PDF_FROMCHARCODE

String.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)
Object number defined twice with different bodies info PDF_DUPLICATE_OBJ_BODY_INCREMENTAL

The same indirect object (N G) is defined more than once with different body bytes. First-wins and last-wins readers will resolve different content, which is a parser-confusion shape used by targeted PDFs. Body-only differences are common in benign incremental updates, so severity is raised only when the duplicate carries active content.
PDF differential parser failed info PDF_DIFFERENTIAL_PARSE_FAILED

The cross-check parser (pdfminer.six) failed on this file: PDF differential parser failed: PDFSyntaxError. Static heuristics still ran and any of their findings above are valid; only the differential cross-check signal is missing.
Suspicious extracted artifact info EXTRACTED_FILE_STATIC_TRIAGE

One 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 4

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj111711_001.js` `81ce03a90a2c0ef5252218223ed8bbac0a54f9cee86d0313d2ecd07551976896`	pdf-javascript-stream	PDF /JS object 111711 at offset 0x197	370 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 eval/decoder/string-building token(s).
`javascript_obj111712_002.js` `8171224f22a8be3cd36646e551f0497e5d8ea92069820da3889ba37374a6d559`	pdf-javascript-stream	PDF /JS object 111712 at offset 0x246	2950 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 eval/decoder/string-building token(s).
`javascript_obj0007_000.js` `27cf39005cb68470eac89dea03979ad2ab1b6ca91ae14ba180b0e795d4059fd5`	pdf-javascript-stream	PDF /JS object 7 at offset 0x1A5	75183 bytes
Detection ClamAV: Win.Trojan.Agent-36166 Obfuscation or payload: unlikely
`polyglot_child_pdf_off00000ad6.pdf` `c96037b859b0ef0278e307ad8b66dd3150b7595d1152f12a3135d2472ab53cc3`	polyglot-child-pdf	Secondary PDF body inside pdf container at offset 0xAD6	2045226 bytes
Detection ClamAV: Win.Trojan.Agent-36166 Obfuscation or payload: unlikely

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