PDF malware analysis — malicious · 257a2a499da31034

MALICIOUS

PDF

7.9 KB

MD5: 9ab8f8746c1825b8971435ea9321744e SHA-1: 004124726784babdd15fc3c9e38297e0c197140e SHA-256: 257a2a499da310341eac76856cfd6f3c02677fd7fae4bc5de5ad994bf378d76a

134 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell

The PDF contains heavily obfuscated JavaScript, identified as a multi-stage dropper. This script is designed to decode and execute a payload, likely for downloading further malicious content. The ClamAV detection 'Pdf.Exploit.Agent-35901' further confirms its malicious nature. The primary attack pattern involves exploiting PDF vulnerabilities to deliver a secondary payload.

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 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` `4718a27c2224fc36bf24f8e8e04598f1ad78adce4401c7be2708318738a6983d`	pdf-javascript-stream	PDF /JS object 5 at offset 0x148	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` `582e26e760a720edcde1c20c0f27b97974a69ec5937836abb72b40e98f3b6697`	deobfuscated-js	repeated-marker hex decoded JavaScript at offset 0x1AD1	1664 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 eval/decoder/string-building token(s).
`deobfuscated.js` `ff5c53a92716ba780d5cec03be07348ac91c3d041ae7109c8db9d9538fdbed95`	deobfuscated-js	PDF JavaScript deobfuscation pass	23465 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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