PDF malware analysis — malicious · 633f5bf8ef0a03fe

MALICIOUS

PDF

3.3 KB Created: 2008-31-20 53:85:00 Authoring application: Scribus 1.3.3.12 (via Scribus PDF Library 1.3.3.12)

MD5: 45981f6b4778a7eada03616a380d458d SHA-1: 8f28078728b04d21afd5b6fa4b9c54c5683167d8 SHA-256: 633f5bf8ef0a03fe1e8e00a3350aa1acd3174d7f0dbc16fc9c9bac747a59f7a5

276 Risk Score

Malware Insights

MITRE ATT&CK

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

This PDF file contains obfuscated JavaScript that utilizes eval() and String.fromCharCode() to deobfuscate and execute malicious code. The ML classifier and ClamAV detection strongly indicate a malicious exploit. The primary function of the embedded script is to download and execute a secondary payload, as evidenced by the deobfuscated JavaScript content and the ClamAV detection signature 'Pdf.Exploit.Agent-35835'.

Machine Learning

Nyx PDF Classifier malicious score 1.0000

Heuristics 8

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.
ClamAV: Pdf.Exploit.Agent-35835 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Pdf.Exploit.Agent-35835
ClamAV detection on extracted artifact critical EXTRACTED_FILE_CLAMAV

ClamAV flagged at least one file extracted from inside this sample. Even when the wrapping document carries no AV detection of its own, a hit on the carved artifact is a strong indicator the sample is a delivery vehicle.
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. (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 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0013_001.js` `fddefa6163200f36b0e7073ed41103e1ff534fe5a77931f1c551a146ffbc71b8`	pdf-javascript-stream	PDF /JS object 13 at offset 0x3D7	5885 bytes
Detection ClamAV: Pdf.Exploit.Agent-35835 Obfuscation or payload: likely Carved artifact contains 2 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).
`deobfuscated.js` `e0da252ee2265dcd4b61f851436909b34607245c8e668e8a4d229ce9da77d610`	deobfuscated-js	PDF JavaScript deobfuscation pass	13656 bytes
Detection ClamAV: Pdf.Exploit.Agent-35835 Obfuscation or payload: likely Carved artifact contains 5 eval/decoder/string-building token(s). Carved artifact contains 2 long base64-like blob(s).

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