PDF malware analysis — malicious · eced64ec139bb461

MALICIOUS

PDF

16.0 KB

MD5: bc5a17a93e106c3e51134a1aeaa9251f SHA-1: 318e84671557e040badb9c8574128f56102eb7e1 SHA-256: eced64ec139bb461e8971fdab4783f68454e5fef2cb74da3a138c10de9e3ab37

74 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 JavaScript T1204.002 Malicious File

The PDF contains obfuscated JavaScript, identified as a multi-stage dropper. This script is designed to download and execute a second-stage payload. The presence of multiple deobfuscated JavaScript files suggests a complex, multi-stage infection chain. The primary attack pattern involves luring the user into opening a malicious PDF that then executes embedded scripts.

Heuristics 6

Obfuscated multi-stage PDF JavaScript dropper high PDF_JS_OBFUSCATED_DROPPER

PDF JavaScript shows 3 independent signals of exploit-kit-style multi-stage obfuscation: annot_subject_stage, hex_dashed_payload, 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` `ab3f4be7a3e2e879e844dcace56ca59cf8fe7249dc5a05c90896f0c9e7dd732a`	pdf-javascript-stream	PDF /JS object 5 at offset 0x148	559 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` `1df0a94211c764db0ab6cc453a62b8bfd2e2b29a9058eebb144ebe873b84d231`	deobfuscated-js	repeated-marker hex decoded JavaScript at offset 0x1B9A	12083 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).
`deobfuscated.js` `15965669e85dfd2e48ed8ee266d9b3b4feb606e11ff795cdebfbdf4371be413f`	deobfuscated-js	PDF JavaScript deobfuscation pass	107136 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 4 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).

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