PDF malware analysis — malicious · af437f52cd76262f

MALICIOUS

PDF

7.8 KB

MD5: 71b6ffe26b7c5265acd1ade9d449c9ff SHA-1: 49b827cfcde1bc2ed9f64a5980e21099c057105c SHA-256: af437f52cd76262fdac165ccc900e1f86209c74f0f6af610c505f4eabb89a548

134 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell

The critical ClamAV detection and high PDF_JS_OBFUSCATED_DROPPER heuristic indicate this PDF is designed to deliver a second-stage payload. The obfuscated JavaScript, including hex decoding and incremental evaluation, strongly suggests a dropper functionality. While the exact download URL or execution command is not directly visible due to obfuscation, the overall pattern points to 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` `4a1d3ca3254de1e5f2cf4129aab72ce60666e42556ca4813e6548f0485416e81`	deobfuscated-js	repeated-marker hex decoded JavaScript at offset 0x1A1A	1821 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 eval/decoder/string-building token(s).
`deobfuscated.js` `c3f355b4a080108d33387d4fa2dc5391c2d4f579b1a6ae9101f2ff0b1b041a6e`	deobfuscated-js	PDF JavaScript deobfuscation pass	24736 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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