PDF malware analysis — malicious · 13178d539f30d0ce

MALICIOUS

PDF

118.6 KB

MD5: d12e77a89b1c3b2978173871b50473de SHA-1: a78668d396d5de0b64eaf5710a26228b0b237e57 SHA-256: 13178d539f30d0ce94f67aa6cfb6955418b384b2f58ea6988274086e8ba04b44

256 Risk Score

Malware Insights

MITRE ATT&CK

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

The sample is a PDF file that contains embedded and obfuscated JavaScript. Heuristics indicate the use of eval() and fromCharCode, common in exploit stagers. The JavaScript is designed to download and execute a secondary payload, as evidenced by the 'PDF JavaScript exploit cluster' and 'Large comment-padded JavaScript eval stager' firings. The ClamAV detection 'Pdf.Exploit.Agent-36086' further confirms its malicious nature.

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-36086 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Pdf.Exploit.Agent-36086
eval() call high PDF_EVAL

eval() found — commonly used for obfuscated exploit execution (matched inside decoded stream)
Large comment-padded JavaScript eval stager high PDF_JS_LARGE_COMMENT_PADDED_EVAL

PDF JavaScript contains a very large stream padded with long random-looking block comments around String.fromCharCode and eval. This is an exploit-kit obfuscation shape used to bury a decoder and recovered stage inside noise, not normal PDF form automation.
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_obj0006_000.js` `eae5bcc19406cc37584517245238e776a20598c85e327fb155a8fcc7177c5f1e`	pdf-javascript-stream	PDF /JS object 6 at offset 0x143	627588 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 2 eval/decoder/string-building token(s). Carved artifact contains 42 long base64-like blob(s).
`legacy_pdfkit_stage_000.js` `09623a4e09601f7db06dd64bc4e8e67bfc7c1d0ec0f7d06834bc4fb03e72f9cd`	deobfuscated-js	double percent-decoded annotation JavaScript at offset 0x143	262144 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 662 long base64-like blob(s).

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