PDF malware analysis — malicious · 3bb5a042460c8773

MALICIOUS

PDF

8.0 KB

MD5: 433b28c19bc553a4885917c32bcddce2 SHA-1: f49890316af23ca1de506a34e79fcfe4a15ac93e SHA-256: 3bb5a042460c8773510fb6246a3ba086b0228c4e83aa61b1f812abc1a3ff8e2a

134 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell

The critical ClamAV_DETECTION heuristic and the high PDF_JS_OBFUSCATED_DROPPER heuristic indicate this PDF is designed to drop and execute a malicious payload. The obfuscated JavaScript dropper uses techniques like String.fromCharCode with hex decoding and incremental evaluation to hide its malicious intent. The extracted JavaScript files likely contain the logic for downloading and executing further stages of the attack.

Heuristics 7

ClamAV: Pdf.Exploit.Agent-35916 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Pdf.Exploit.Agent-35916
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` `6c41320119e160dc719997b9a2efb3600ea9d7e9d7e44b4dc2125762dc9f365f`	pdf-javascript-stream	PDF /JS object 5 at offset 0x148	505 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 2 eval/decoder/string-building token(s).
`legacy_pdfkit_stage_000.js` `a694064564e2fad3a9cc09992202146fe93e527581d5aa234e402e5fdf896e5a`	deobfuscated-js	repeated-marker hex decoded JavaScript at offset 0x1B03	1748 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 eval/decoder/string-building token(s).
`deobfuscated.js` `3acfe863d10342c5cb5c5e65a1769d5154b947a7f317bb2d79a1cfe7d5dae4b7`	deobfuscated-js	PDF JavaScript deobfuscation pass	27117 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 7 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).

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