PDF malware analysis — malicious · 3f78cdbfb3c9e7e2

MALICIOUS

PDF

16.2 KB

MD5: 2a1dc4fced17f6ddbfda45f1c79af73a SHA-1: edadde5296e19af42dc096022f5a842e9def4281 SHA-256: 3f78cdbfb3c9e7e286542c9c5fbeec96ae9fe42721cee148ceb9c9c88d6e2793

158 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell

The PDF contains heavily obfuscated JavaScript, flagged as a multi-stage dropper. Analysis indicates it's designed to download and execute further malicious content. The presence of multiple JavaScript streams and the ML classifier's high confidence score support this assessment. The extracted files 'deobfuscated.js' and 'legacy_pdfkit_stage_000.js' are likely components of this dropper chain.

Machine Learning

Nyx PDF Classifier malicious score 1.0000

Heuristics 6

ClamAV: Pdf.Dropper.Agent-7253325-0 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Pdf.Dropper.Agent-7253325-0
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 3

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0005_000.js` `a3319192cac6d4dc4eeb6af2d736b0ffec979b23116a003bc7c23382761c32a5`	pdf-javascript-stream	PDF /JS object 5 at offset 0x148	733 bytes
`legacy_pdfkit_stage_000.js` `8f1b781f870b47619214da1218fce8711a3b97d8ee6ef95e8ab67b2d805dd6d3`	deobfuscated-js	repeated-marker hex decoded JavaScript at offset 0x1B95	12888 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` `aa9878afb0cf37a0c09cd61d995b0e944f0a30f124c9e25f41bcc6bf5d5a500d`	deobfuscated-js	PDF JavaScript deobfuscation pass	64698 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 long base64-like blob(s).

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