PDF malware analysis — malicious · a4ed9590ce2be282

MALICIOUS

PDF

15.5 KB

MD5: 860919fdd15d290f4373a554bd3ad8a1 SHA-1: 7cb75026e115f74ae59df38b47cddb563a93f670 SHA-256: a4ed9590ce2be282db8f3eb83c0f8468c67f28748d24b7188664c33dddcb3b74

94 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell T1204.002 Malicious File

This PDF file contains embedded JavaScript, indicated by multiple heuristic firings including PDF_JAVASCRIPT and PDF_JS. The PDF_ANNOT_SUBJECT_HEX_EVAL_STAGER heuristic suggests that the annotation subject is used to decode and execute a stager. The extracted JavaScript files, such as 'numeric_charcode_stage_000.js' and 'legacy_pdfkit_stage_000.js', are likely responsible for further stages of the attack, potentially downloading and executing additional payloads. The exact intent of the script is not fully clear due to obfuscation, but its presence and the critical heuristic firing strongly suggest malicious execution.

Heuristics 6

Annotation subject hex-decoded eval stager critical PDF_ANNOT_SUBJECT_HEX_EVAL_STAGER

PDF OpenAction JavaScript decodes a decimal char-code launcher, enumerates annotation subjects with syncAnnotScan()/getAnnots(), turns dash-delimited hex bytes into JavaScript with String.fromCharCode(), and evals the staged result. This is an exploit-kit delivery pattern and not normal PDF form logic.
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. (identified after JavaScript deobfuscation)
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_obj0004_000.js` `b771a67801a2a024471cb29d8ce119b13dc98b5c56ef213dece7e1a5cc7b8bed`	pdf-javascript-stream	PDF /JS object 4 at offset 0xE1	1814 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 eval/decoder/string-building token(s).
`numeric_charcode_stage_000.js` `4718a27c2224fc36bf24f8e8e04598f1ad78adce4401c7be2708318738a6983d`	deobfuscated-js	numeric char-code string decoded JavaScript at offset 0xEF	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` `0be39620d4258796ba3cea710099e4c6d711c0df8649cf2af9224d7fb3ffb576`	deobfuscated-js	repeated-marker hex decoded JavaScript at offset 0x1A8D	11963 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).

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