PDF malware analysis — malicious · 5fde821198348834

MALICIOUS

PDF

16.5 KB

MD5: 27dc759ae95bc4a2d59b547fe1db51d4 SHA-1: ebd615f8b049573e792ecaa1708517eb9454b616 SHA-256: 5fde82119834883466e000a7a8168be760171f10eccca567a0bed746a3a91246

136 Risk Score

Malware Insights

MITRE ATT&CK

T1059.007 JavaScript T1566.001 Spearphishing Attachment

The PDF contains obfuscated JavaScript that attempts to download and execute a payload. The script utilizes anti-analysis techniques such as checking app.plugIns.length and employs string manipulation to construct its malicious commands. The primary function appears to be downloading and executing a second-stage payload, indicated by the 'eval' call on the constructed string.

Machine Learning

Nyx PDF Classifier malicious score 1.0000

Heuristics 6

Generic recovered JavaScript exploit stage high PDF_GENERIC_STAGE_RECOVERY

Bounded static stage recovery exposed hidden JavaScript through generic transforms such as null-byte collapse, percent decoding, marker replacement, arithmetic character codes, fromCharCode, numeric arrays, numeric-array minus-key decoders, alphabet-index arrays, /Producer half-difference metadata arrays, hex literals, marker-stripped Base64 literals, custom 6-bit XOR table decoders, or repeated-marker hex carriers. This rule is emitted only when the recovered stage contains exploit-like Acrobat JavaScript or shellcode markers.
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.
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 4

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0005_000.js` `a2765ef4bc176af71164210608f93ccd0cfd1d5803648c48f5d630ef03f5faa9`	pdf-javascript-stream	PDF /JS object 5 at offset 0x148	749 bytes
`generic_stage_recovery_000.js` `2cddb2bc6087d7e401900b317c670724f2f13cb3e511de2bcf362f30cd1285e7`	deobfuscated-js	generic stage recovery split-literal-normalize from JavaScript object 5 at offset 0x148	737 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 eval/decoder/string-building token(s).
`legacy_pdfkit_stage_000.js` `29cbf6d7ae1afd8f6381751daff5e3b09926ab21b0a3c33ccc1297ffe26d57c4`	deobfuscated-js	repeated-marker hex decoded JavaScript at offset 0x1C1F	13036 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` `7ac49ac68bb70e50a211c9fc4e7104b65645f734f9b52732ff2a6672dd6a8279`	deobfuscated-js	PDF JavaScript deobfuscation pass	65836 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 long base64-like blob(s).

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