PDF malware analysis — malicious · 56878d330e9b4167

MALICIOUS

PDF

1.95 MB Created: 2011-72-51 03:25:00 Authoring application: String.fromCharCode

MD5: b90aab250854bf78d662c93110379ea6 SHA-1: 7a3c4935deda318da4eaa6655cb2b9d63950ebd8 SHA-256: 56878d330e9b4167fd66663afd44f77dd2f0971819957082d5639ce2ae4851fe

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, identified by the PDF_JAVASCRIPT and PDF_JS heuristics. The JavaScript stream utilizes `eval()` and `String.fromCharCode` for obfuscation, a common technique to hide malicious code. The ML classifier strongly indicates maliciousness. The primary intent appears to be downloading and executing a second-stage payload, as suggested by the obfuscated script and the presence of an extracted JavaScript file. The confidence is slightly reduced due to the lack of explicit network indicators or further script details.

Machine Learning

Nyx PDF Classifier malicious score 0.9998

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` `278ca72c2d6c31fbc49926b45eb233b95805818ff32efa97edafd20643fc82d9`	pdf-javascript-stream	PDF /JS object 1 at offset 0xA	980 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 5 eval/decoder/string-building token(s).

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