PDF malware analysis — malicious · f467430af1ab1299

MALICIOUS

PDF

17.8 KB

MD5: a863455a27a5224fe0823f5ad8816a67 SHA-1: 1f5b278e588068a08c39d95068945acfec5f3130 SHA-256: f467430af1ab1299e787c05d86103aff88c1d5eba96cb2fa906783481540fc2f

134 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell

The PDF file contains heavily obfuscated JavaScript, identified as a multi-stage dropper. The script employs anti-analysis techniques such as repeated checks on app.plugIns.length and incremental evaluation. The primary function appears to be decoding and executing further stages, indicated by the use of String.fromCharCode with hex decoding and incremental evaluation. This behavior strongly suggests the file is designed to download and execute a secondary payload, aligning with common dropper functionalities.

Heuristics 7

ClamAV: Pdf.Exploit.Agent-35901 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Pdf.Exploit.Agent-35901
Obfuscated multi-stage PDF JavaScript dropper high PDF_JS_OBFUSCATED_DROPPER

PDF JavaScript shows 4 independent signals of exploit-kit-style multi-stage obfuscation: annot_subject_stage, hex_codec_loop, 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_obj0009_000.js` `4718a27c2224fc36bf24f8e8e04598f1ad78adce4401c7be2708318738a6983d`	pdf-javascript-stream	PDF /JS object 9 at offset 0x44E9	469 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` `ffb179ac32d55569513f35046c261be6d815c45dca06c31f8e112fb247b3d4e7`	deobfuscated-js	repeated-marker hex decoded JavaScript at offset 0x1AFF	11649 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 2 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).
`deobfuscated.js` `62a0baa499cdbe8d7fa33e3ce920afb5f4745b8a24237b613682a3abb8607873`	deobfuscated-js	PDF JavaScript deobfuscation pass	104252 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 4 eval/decoder/string-building token(s). Carved artifact contains 2 long base64-like blob(s).

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