PDF malware analysis — malicious · 0c503b9b0206fe7c

MALICIOUS

PDF

5.2 KB Created: 2008-12-03 13:57:41 UTC

MD5: 8cb0b82bbf172353961638cebb8d0adc SHA-1: 4ab0c691cf0ce3cf1b4b87c4c1813a27156b4bd9 SHA-256: 0c503b9b0206fe7cd0b8850a382184cf41d6c320e25c722699c73902338051ef

156 Risk Score

Malware Insights

MITRE ATT&CK

T1059.007 JavaScript T1566.001 Spearphishing Attachment

The PDF file contains embedded JavaScript that is heavily obfuscated using Base64 encoding and string concatenation. The script utilizes `eval()` and `String.fromCharCode()` to dynamically construct and execute code, a common technique for exploiting vulnerabilities and downloading further payloads. The ML classifier strongly indicates maliciousness, and the presence of JavaScript exploit cluster heuristics further supports this. The script's primary function appears to be the execution of arbitrary code, likely leading to a second-stage download.

Machine Learning

Nyx PDF Classifier malicious score 0.9999

Heuristics 6

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.
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 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0006_000.js` `ee6a21db81fe0bd65e69ced30695e01ddc2af36a92842df490ce67417653768a`	pdf-javascript-stream	PDF /JS object 6 at offset 0xC5	8607 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 4 eval/decoder/string-building token(s).

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