PDF malware analysis — malicious · 2a255402d9a6484d

MALICIOUS

PDF

22.3 KB Created: 2011-72-51 03:25:00 Authoring application: String.fromCharCode

MD5: b755098ef2f9a57930a10459e3f408e8 SHA-1: f1dfb99fc3243b534fda7f87d346744b69b34028 SHA-256: 2a255402d9a6484d52d665d8a6289ae06f53d731b56cd9bf50a42158b36cf285

96 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 Command and Scripting Interpreter: PowerShell T1059.003 Command and Scripting Interpreter: Windows Command Shell T1059.007 Command and Scripting Interpreter: JavaScript/TypeScript

This PDF file contains embedded JavaScript, indicated by the PDF_JAVASCRIPT and PDF_JS heuristics. The JavaScript stream utilizes `String.fromCharCode` and an `eval()` call, suggesting obfuscation and dynamic code execution. The ML classifier strongly flags this PDF as malicious. The primary intent appears to be downloading and executing a second-stage payload, as evidenced by the embedded JavaScript artifact.

Machine Learning

Nyx PDF Classifier malicious score 1.0000

Heuristics 5

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.
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_obj0001_000.js` `9ff98d70cff3481339febab52900e7515a2f3c75db7445fa9f30eefbd4469fd2`	pdf-javascript-stream	PDF /JS object 1 at offset 0xA	515 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 6 eval/decoder/string-building token(s).

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