PDF malware analysis — malicious · 31ffd93c461295e1

MALICIOUS

PDF

7.8 KB

MD5: ce66108f968b552c45b750934f510de2 SHA-1: a0cfaf90e1cc78b9d280457003aa364f6c4a7615 SHA-256: 31ffd93c461295e18502d255858459588088bd5218d00d59f4928b4803567541

134 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell

The PDF contains heavily obfuscated JavaScript, identified by heuristics such as 'PDF_JS_OBFUSCATED_DROPPER'. This script is designed to decode and execute a secondary payload, likely for downloading further malicious content. The 'CLAMAV_DETECTION' heuristic confirms its malicious nature, specifically identifying it as 'Pdf.Exploit.Agent-35902'. The presence of multiple JavaScript streams and deobfuscated JS files indicates a multi-stage attack.

Heuristics 7

ClamAV: Pdf.Exploit.Agent-35902 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Pdf.Exploit.Agent-35902
Obfuscated multi-stage PDF JavaScript dropper high PDF_JS_OBFUSCATED_DROPPER

PDF JavaScript shows 5 independent signals of exploit-kit-style multi-stage obfuscation: annot_subject_stage, hex_codec_loop, hex_dashed_payload, incremental_eval_build, 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` `3cf6a22459cda11e607fc9e0dc0c88d01a8425e26488ff87df38d855ceb4dccf`	pdf-javascript-stream	PDF /JS object 5 at offset 0x148	465 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` `9519149cde91d78889d9230e108308d6da9cebedf905493f745d6e49e9bb7de4`	deobfuscated-js	repeated-marker hex decoded JavaScript at offset 0x1A4C	1755 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 eval/decoder/string-building token(s).
`deobfuscated.js` `48da1ac5d47b079e1c95619d8de02577c8f7a7c2d8fbde686639e5e3f7222c2c`	deobfuscated-js	PDF JavaScript deobfuscation pass	43032 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 5 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).

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