PDF malware analysis — malicious · b5ca2d93108b5537

MALICIOUS

PDF

118.6 KB

MD5: df9fb4a55a906e42ce628e4a45112f9c SHA-1: f843c343c0c421d6787c1048098616a3333e4781 SHA-256: b5ca2d93108b5537c8e95ffda2e70e5db9fde5b1c32b34ee431620dc61160a13

196 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell T1204.002 Malicious File

The PDF file contains embedded JavaScript, including calls to eval() and String.fromCharCode, which are commonly used to obfuscate malicious code. Heuristics indicate a large, comment-padded JavaScript eval stager, and ML classification strongly suggests maliciousness. ClamAV detection confirms this, identifying it as Pdf.Exploit.Agent-36086. The embedded JavaScript is likely responsible for downloading and executing a second-stage payload.

Machine Learning

Nyx PDF Classifier malicious score 1.0000

Heuristics 7

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` `5f3b1a8e5ce9d6e2e625e4a676a37980f937106b60702479bd7b80814f2b64b1`	pdf-javascript-stream	PDF /JS object 6 at offset 0x143	626372 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` `ed2fdc8f15efe2bdf45191c0905701333e0355655cd4c49512fc3fc4e66c0ae3`	deobfuscated-js	double percent-decoded annotation JavaScript at offset 0x143	262144 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 468 long base64-like blob(s).

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