PDF malware analysis — malicious · 399ef72ca0b4f273

MALICIOUS

PDF

44.2 KB

MD5: 129e6ab78303abe4c5bf5740cfe07a13 SHA-1: 68d7f51d8108d988fb0aef1bc6f5ad3fb156e9ff SHA-256: 399ef72ca0b4f27300839ccff06a83146d2729fae05f1d2bb2c713cb011e28f7

114 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 JavaScript T1204.002 Malicious File

The PDF file contains obfuscated JavaScript, identified as a dropper, which is designed to download and execute further stages. The presence of U3D content and multiple heuristic firings related to JavaScript and obfuscation indicate a multi-stage attack. The deobfuscated JavaScript and extracted artifacts suggest a downloader functionality, though the final payload and its specific C2 infrastructure were not directly observed in this analysis.

Heuristics 7

U3D/3D content in PDF — Adobe Reader 3D parser CVE-family indicator high CVE related PDF_U3D_CVE_RELATED

PDF contains U3D (Universal 3D) or 3D annotation content — CVE-2011-2462 and CVE-2009-3953 are critical vulnerabilities in Adobe Reader's U3D processing that allow arbitrary code execution. U3D content in PDFs is extremely rare in normal documents.
Obfuscated multi-stage PDF JavaScript dropper high PDF_JS_OBFUSCATED_DROPPER

PDF JavaScript shows 3 independent signals of exploit-kit-style multi-stage obfuscation: annot_subject_stage, hex_dashed_payload, repeated_pluginschk. This is strongly consistent with pre-2011 Adobe Reader PDF droppers — OpenAction JS reads encoded data from annotation subjects, decodes it through one or more hex / base-N loops, and invokes eval indirectly (method name built one character at a time). The actual CVE is hidden in the final decoded layer and is not visible via static analysis.
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)
syncAnnotScan annotation-staging primitive low PDF_FOXIT_SYNCANNOTSCAN

PDF JavaScript calls syncAnnotScan() — a no-op annotation-enumeration primitive used by exploit-kit JavaScript to stage payload reads from annotation /Subject fields before eval(). Not a vulnerable sink itself; rarely seen in legitimate PDFs. (matched in decompressed stream)
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_obj0005_000.js` `041ad794d3db20d026f21a8e2c9d9da29721c2444af8d5467b57ae7f54e982d9`	pdf-javascript-stream	PDF /JS object 5 at offset 0x14F	701 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 3 eval/decoder/string-building token(s).
`legacy_pdfkit_stage_000.js` `3ae84b62a542bd30370faa420ce3409ff0f6b8c21991c467e4992662abc7dee4`	deobfuscated-js	repeated-marker hex decoded JavaScript at offset 0x1D88	13041 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).
`deobfuscated.js` `b542c0dc32ffa37fdeaed6d16b35c94b502c0b36deb6cabd94f92af864312c12`	deobfuscated-js	PDF JavaScript deobfuscation pass	214972 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 6 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).
`u3d_00_off00004455.bin` `fb27c6f6ffe2b08a88f79f344ef3cb4f85460ac81a062194b6fd84ab6e48b628`	pdf-3d-stream	PDF U3D 3D stream at offset 0x4455	28021 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 7.79, consistent with packed or encrypted content.

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