PDF malware analysis — malicious · 6936249b7ebad2ec

MALICIOUS

PDF

12.6 KB

MD5: f5d4960db4b6cb1de52cd14cd95dd7f2 SHA-1: 1f2492fccdb7c2218bc92aee7ec40aaefc121d78 SHA-256: 6936249b7ebad2ec5a628217bf4e62b1b52b0809f11c072f06df6f959a139c6b

116 Risk Score

Malware Insights

MITRE ATT&CK

T1059.007 JavaScript T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The PDF sample contains obfuscated JavaScript that utilizes `String.fromCharCode` and a custom `decrypt` function. This script is designed to exploit a PDF vulnerability, likely for client-side execution. The script's reconstructed code, after decryption, appears to be attempting to download and execute a second-stage payload from a URL, indicated by calls to `app.response.getURL`. The ML classifier and exploit cluster heuristics strongly suggest malicious intent.

Machine Learning

Nyx PDF Classifier malicious score 1.0000

Heuristics 5

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.
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 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0005_000.js` `d2233358777d1aaed8efae57eefbdc7f0ddc83b20eb36c734bc8ee388da7c061`	pdf-javascript-stream	PDF /JS object 5 at offset 0x107	1418 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 eval/decoder/string-building token(s).

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