PDF malware analysis — malicious · b655193bed82d30f

MALICIOUS

PDF

15.7 KB

MD5: d3381a8d363e14516bd67663dc744f04 SHA-1: a9f22658d6eec9a1f92aebabd6ad3e3a3978f295 SHA-256: b655193bed82d30f1b3c4ae60b0c5cc40976566af0955c9d1206dff99514da1a

74 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell

The PDF contains obfuscated JavaScript, identified as a multi-stage dropper. This script is designed to deobfuscate and execute further stages, likely downloading and running a malicious payload. The presence of multiple embedded JavaScript files and the 'PDF_JS_OBFUSCATED_DROPPER' heuristic strongly indicate this dropper functionality. The specific URLs or final payloads were not directly extracted, hence the 'unknown family' classification.

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` `81fdb05c9ba27a2dd95b2d25bc25604a628d50371f8d663c55e6fb138eefaa2a`	pdf-javascript-stream	PDF /JS object 5 at offset 0x148	694 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 3 eval/decoder/string-building token(s).
`legacy_pdfkit_stage_000.js` `901afbbcd590605b0dce620fa2b0392202181d931de1673032dcd513d88a5683`	deobfuscated-js	repeated-marker hex decoded JavaScript at offset 0x1B04	12125 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` `fe323d745b6a8bec5c76630952ec4a759b238bee7776b2d53e7441c0a5ddd88d`	deobfuscated-js	PDF JavaScript deobfuscation pass	61412 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 6 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).

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