PDF malware analysis — malicious · b5258050820fea05

MALICIOUS

PDF

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

MD5: bd5d12af466bf189fa727ac9f8f0ba31 SHA-1: 4b39fb0280dead98e5e15bc0e495a2086db9bdd0 SHA-256: b5258050820fea052843818995e3a2f41eeac3eb298df14812a73323a50b382b

156 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 Command and Scripting Interpreter: PowerShell T1059.003 Command and Scripting Interpreter: Windows Command Shell T1204.002 Malicious File: Malicious File

The PDF contains embedded JavaScript, which is obfuscated and uses an eval() call. This strongly suggests the script is designed to download and execute a second-stage payload. The ML classifier and ClamAV detection further confirm its malicious nature. The use of String.fromCharCode is a common technique in obfuscated JavaScript within PDFs.

Machine Learning

Nyx PDF Classifier malicious score 1.0000

Heuristics 6

ClamAV: Pdf.Exploit.Agent-30003 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Pdf.Exploit.Agent-30003
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` `898ad7c270946ee0c7a45ce58c15de823c8ff75879e0272a4fbc2593c288b818`	pdf-javascript-stream	PDF /JS object 1 at offset 0xA	514 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 6 eval/decoder/string-building token(s).

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