PDF malware analysis — malicious · 1b453b06dae89c62

MALICIOUS

PDF

16.6 KB

MD5: e804f91f66fe99b173db9fc1e4020224 SHA-1: 66562fd5214ccee3fa67912ac0d9ca471caf4526 SHA-256: 1b453b06dae89c626e76341218c4c87a54fe19245e03dd016a0789ebde753d85

66 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell T1204.002 Malicious File

The PDF contains embedded JavaScript, identified by heuristics like PDF_JAVASCRIPT and PDF_JS. The ML classifier strongly indicates maliciousness. The JavaScript appears to be obfuscated and uses String.fromCharCode to reconstruct exploit code, as indicated by PDF_FROMCHARCODE and PDF_FOXIT_SYNCANNOTSCAN. This script is likely responsible for downloading and executing a second-stage payload, though the specific URLs are not directly extractable from the provided evidence.

Machine Learning

Nyx PDF Classifier malicious score 0.9999

Heuristics 5

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. (identified after JavaScript deobfuscation)
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 3

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0004_000.js` `b771a67801a2a024471cb29d8ce119b13dc98b5c56ef213dece7e1a5cc7b8bed`	pdf-javascript-stream	PDF /JS object 4 at offset 0xE1	1814 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 eval/decoder/string-building token(s).
`numeric_charcode_stage_000.js` `4718a27c2224fc36bf24f8e8e04598f1ad78adce4401c7be2708318738a6983d`	deobfuscated-js	numeric char-code string decoded JavaScript at offset 0xEF	469 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 eval/decoder/string-building token(s).
`legacy_pdfkit_stage_000.js` `1e2faaa5bfce56154f6eaefd91502c27f189c0ddeaa7cdcdf960ee82a1a2d9b1`	deobfuscated-js	repeated-marker hex decoded JavaScript at offset 0x1CD2	12403 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).

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