PDF malware analysis — malicious · c5f92b3355ee4d0d

MALICIOUS

PDF

20.7 KB

MD5: c0d3fbe6f802dda3ccb5bb4ac6f2f80c SHA-1: 1cf58b69dfee696e9c9015fb325775264144bec2 SHA-256: c5f92b3355ee4d0d3c6bffaaadc40ea51f219c900503efcb25c3adff770b5949

64 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell T1204.002 Malicious File

The PDF contains embedded JavaScript, indicated by multiple heuristic firings including 'PDF_JAVASCRIPT' and 'PDF_JS'. The 'PDF_FOXIT_SYNCANNOTSCAN' heuristic specifically mentions the use of String.fromCharCode to decode JavaScript, which is then evaluated. This suggests the script is designed to exploit a vulnerability in Adobe Reader. The ML classifier also flagged this PDF as malicious with high confidence. No specific malware family could be identified, but the techniques used are consistent with exploit delivery.

Machine Learning

Nyx PDF Classifier malicious score 0.9998

Heuristics 5

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)
syncAnnotScan annotation-staging primitive low PDF_FOXIT_SYNCANNOTSCAN

PDF JavaScript calls syncAnnotScan() — a no-op annotation-enumeration primitive used by exploit-kit JavaScript to stage payload reads from annotation /Subject fields before eval(). Not a vulnerable sink itself; rarely seen in legitimate PDFs. (identified after JavaScript deobfuscation)
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_obj0004_000.js` `b771a67801a2a024471cb29d8ce119b13dc98b5c56ef213dece7e1a5cc7b8bed`	pdf-javascript-stream	PDF /JS object 4 at offset 0xE1	1814 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 eval/decoder/string-building token(s).
`numeric_charcode_stage_000.js` `4718a27c2224fc36bf24f8e8e04598f1ad78adce4401c7be2708318738a6983d`	deobfuscated-js	numeric char-code string decoded JavaScript at offset 0xEF	469 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 eval/decoder/string-building token(s).

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