PDF malware analysis — malicious · b3391288633c1b22

MALICIOUS

PDF

7.9 KB

MD5: 5411dcd5ebd2e37775cc7dd7f40e43ce SHA-1: 1beab56d0959ab8fd48633b8dc9d6501178960ba SHA-256: b3391288633c1b22d7be52afadfaf7709cf8c2c4b331fe61af50509ae527c650

134 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell

The PDF contains heavily obfuscated JavaScript, identified by the 'PDF_JS_OBFUSCATED_DROPPER' heuristic. This script is designed to decode and execute a secondary payload, likely for downloading further malware. The 'ClamAV_DETECTION' heuristic confirms its malicious nature, flagging it as 'Pdf.Exploit.Agent-35916'. The presence of multiple JavaScript streams and the use of String.fromCharCode with hex decoding indicate a multi-stage 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` `c83e7776ea31450564b77e597bcaafdaea896f284c300d756caa1b1e884649e9`	deobfuscated-js	repeated-marker hex decoded JavaScript at offset 0x1AB4	1722 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 eval/decoder/string-building token(s).
`deobfuscated.js` `9547bd99da913da9c0431a207a95275433a285b75effe2523ecbeadbc221aebc`	deobfuscated-js	PDF JavaScript deobfuscation pass	27083 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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