PDF malware analysis — malicious · c4088d88aeed0f0a

MALICIOUS

PDF

118.7 KB

MD5: 145fb34ec145dd60bd662ec509787c0e SHA-1: 45d4de463c25ebd534f85954a0b95aa52758935e SHA-256: c4088d88aeed0f0a23c907f543bdb508d6d06c8197675e1abf28b24cb3cff428

166 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell T1204.002 Malicious File T1566.001 Spearphishing Attachment T1071.001 Web Protocols

The file is a PDF containing embedded JavaScript, as indicated by multiple heuristic firings including 'PDF_JAVASCRIPT', 'PDF_JS', and 'PDF_JS_LARGE_COMMENT_PADDED_EVAL'. The critical 'CLAMAV_DETECTION' heuristic identifies it as 'Pdf.Exploit.Agent-36086'. The JavaScript likely acts as a stager, using 'eval()' and 'String.fromCharCode()' to decode and execute a payload, which is a common technique for downloading and running further malicious content. The presence of a large encoded blob and script obfuscation indicators further supports this. The document body was unreadable, but the technical indicators strongly suggest an exploit delivery mechanism.

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` `228a96a0903d3c8a59670c65729d485a63e9ad547712a941861166b28483b767`	pdf-javascript-stream	PDF /JS object 6 at offset 0x143	627416 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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