PDF malware analysis — malicious · f8ad57dea86e1470

MALICIOUS

PDF

8.1 KB

MD5: 456b44b3b7a70a848ee9299db39fe00e SHA-1: 101f9147f23637e71dc573e25c3a5c2d5a05bce8 SHA-256: f8ad57dea86e147024142c6cacc9eab97b41fc7ea1b84b54d0776a924e29515c

134 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell T1566.001 Spearphishing Attachment T1140 Deobfuscate/Decode Files or Information

The critical ClamAV detection and high-severity heuristic for an obfuscated multi-stage PDF JavaScript dropper indicate malicious intent. The embedded JavaScript, though obfuscated, is designed to act as a dropper, likely downloading and executing a second-stage payload. The presence of multiple deobfuscated JavaScript files further supports this dropper functionality.

Heuristics 7

ClamAV: Pdf.Exploit.Agent-35916 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Pdf.Exploit.Agent-35916
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` `6c41320119e160dc719997b9a2efb3600ea9d7e9d7e44b4dc2125762dc9f365f`	pdf-javascript-stream	PDF /JS object 5 at offset 0x148	505 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` `5fe86b5c753b4f829422e5c65ef2479f665bbb513d5eb3bddb3db2cabed9f610`	deobfuscated-js	repeated-marker hex decoded JavaScript at offset 0x1B5B	1810 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 eval/decoder/string-building token(s).
`deobfuscated.js` `6d29f23d57abc17bcf48e29b979d5eb4e79df09e1bbd4bff9a141fdfd4b4879c`	deobfuscated-js	PDF JavaScript deobfuscation pass	25207 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 7 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).

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