PDF malware analysis — malicious · 9984b36b78f96b89

MALICIOUS

PDF

16.8 KB

MD5: f10d48ee0a8c85ec782666b7f3bf0d3d SHA-1: 387846b9646a01b6fe0b2e2aa1886c769cc428f6 SHA-256: 9984b36b78f96b89edf94258c4fdf7f3a4d9aef6ddd27c46d9910ff547946898

104 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell

The PDF contains obfuscated JavaScript, flagged as a high-confidence dropper. The script performs anti-analysis checks by examining app.plugins.length. It is designed to download and execute a second-stage payload, indicated by the 'PDF_JS_OBFUSCATED_DROPPER' heuristic. The ML classifier also strongly indicates maliciousness.

Machine Learning

Nyx PDF Classifier malicious score 1.0000

Heuristics 6

Obfuscated multi-stage PDF JavaScript dropper high PDF_JS_OBFUSCATED_DROPPER

PDF JavaScript shows 3 independent signals of exploit-kit-style multi-stage obfuscation: annot_subject_stage, hex_dashed_payload, repeated_pluginschk. This is strongly consistent with pre-2011 Adobe Reader PDF droppers — OpenAction JS reads encoded data from annotation subjects, decodes it through one or more hex / base-N loops, and invokes eval indirectly (method name built one character at a time). The actual CVE is hidden in the final decoded layer and is not visible via static analysis.
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. (matched in decompressed 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 3

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0005_000.js` `9ef273d46c4080addeccbc25a0f643481671c9a9084a6b29dd9ed311647a7eeb`	pdf-javascript-stream	PDF /JS object 5 at offset 0x148	712 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 3 eval/decoder/string-building token(s).
`legacy_pdfkit_stage_000.js` `ebbf1fff6366e6da6e40ed5c79deec55918dd77d24a7ec0ae38bd03c30b35086`	deobfuscated-js	repeated-marker hex decoded JavaScript at offset 0x1CEA	12890 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).
`deobfuscated.js` `7ac28d540fc4079294a05da4c48b28f4c0be2edd623c8bc45b42c01066bd314f`	deobfuscated-js	PDF JavaScript deobfuscation pass	107979 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 6 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).

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