PDF malware analysis — malicious · 5b57f2bfb1370910

MALICIOUS

PDF

MD5: 102883b6ad4e64b1e4454b583718ed6b SHA-1: 004ec8fd9f8bdabaa1bddd30d27c63ba199ff596 SHA-256: 5b57f2bfb1370910b99b37b64e09053c777fae4f1b93d7f38c380e96ffca4837

156 Risk Score

Malware Insights

MITRE ATT&CK

T1059.007 JavaScript T1203 Exploitation for Client Execution

The PDF file contains embedded JavaScript that is heavily obfuscated using string concatenation and character code manipulation. The script utilizes `eval()` and `String.fromCharCode()` to deobfuscate and execute its payload. The critical PDF_JS_EXPLOIT_CLUSTER heuristic firing indicates a known exploit pattern within the JavaScript. The script's primary function appears to be downloading and executing a secondary payload, as suggested by the deobfuscated code attempting to fetch external resources.

Machine Learning

Nyx PDF Classifier malicious score 1.0000

Heuristics 6

PDF JavaScript exploit cluster critical PDF_JS_EXPLOIT_CLUSTER

PDF combines an executable JavaScript/action surface with exploit staging indicators such as eval/unescape/fromCharCode, XFA script content, or a related CVE pattern. Benign form JavaScript remains low-severity, but this correlated cluster is high-confidence malicious behavior.
eval() call high PDF_EVAL

eval() found — commonly used for obfuscated exploit execution (matched inside decoded stream)
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)
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 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0005_000.js` `1836b3dac2769a2e92248102ff02e2117854588052132d05b080572de912dd77`	pdf-javascript-stream	PDF /JS object 5 at offset 0x277	1462 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 eval/decoder/string-building token(s).
`stream_001_off0000050e.js` `b25541293197383c31bc3e54eba72b65833dda17bc8a916bf6b3c1e1e5b866d9`	decompressed-pdf-stream	PDF FlateDecoded stream at offset 0x50E	117859 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 2 eval/decoder/string-building token(s).

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