PDF malware analysis — malicious · aaa523b1ff225007

MALICIOUS

PDF

118.6 KB

MD5: d83f3f46269aa4ec5476daa6dc34c09a SHA-1: 02993fbcdbd7d9a191037c566bd04950b45a4f7b SHA-256: aaa523b1ff225007b45546d3aafda6623b262af896b7e0c6931f23a50a2843d5

196 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell T1204.002 Malicious File T1566.001 Spearphishing Attachment

The sample is a PDF file flagged by ClamAV as 'Pdf.Exploit.Agent-36086'. Static analysis revealed embedded JavaScript with multiple high-severity heuristics, including `PDF_EVAL`, `PDF_JS_LARGE_COMMENT_PADDED_EVAL`, and a general ML classifier indicating maliciousness. The JavaScript stream, identified as `javascript_obj0006_000.js`, is heavily obfuscated but the presence of `eval()` and `String.fromCharCode` strongly suggests it's designed to download and execute a secondary payload. The `PDF_JAVASCRIPT` and `PDF_JS` firings further confirm the use of JavaScript within the PDF structure.

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 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0006_000.js` `38093a9fae0e3cf5b03f497e0634991a5f920da06cf0b1e773420f58a58bd3b0`	pdf-javascript-stream	PDF /JS object 6 at offset 0x143	627160 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).

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