PDF malware analysis — malicious · fd553a5b7b282681

MALICIOUS

PDF

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

MD5: c106e7b65a055c42349559d9e5e7b6aa SHA-1: 2e10a504f23bbbe215bd327c500ce7889aabcb76 SHA-256: fd553a5b7b2826813c35ac6a34d3054cee4b7527c4129dfa8d51ecb4106ff03d

156 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell T1204.002 Malicious File

This PDF sample was flagged as malicious by a ClamAV signature (Pdf.Dropper.Agent-7328347-0) and a machine learning classifier. Static analysis revealed embedded JavaScript with an eval() call, indicating obfuscated code execution. The JavaScript action and embedded JS stream, combined with the use of String.fromCharCode, suggest the script is designed to download and execute a secondary payload. The ML classifier's high confidence score further supports this assessment.

Machine Learning

Nyx PDF Classifier malicious score 1.0000

Heuristics 6

ClamAV: Pdf.Dropper.Agent-7328347-0 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Pdf.Dropper.Agent-7328347-0
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` `610b68336caeb51d362ef3f74f8b87cb663be95a4d081168ce20129c3e2d6a76`	pdf-javascript-stream	PDF /JS object 1 at offset 0xA	870 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 5 eval/decoder/string-building token(s).

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