PDF malware analysis — malicious · 599c242ae044869d

MALICIOUS

PDF

8.3 KB

MD5: b222d77284b4e5fcc2357d0422aae210 SHA-1: 008f06d2ff5e1001ff672aa71a988472805167e7 SHA-256: 599c242ae044869ddc8b6e810ee4cf31d53fa960379577de84e773f15d4da093

134 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell: PowerShell T1140 Deobfuscate/Decode Files or Information

The PDF contains heavily obfuscated JavaScript, identified as a multi-stage dropper. The script employs techniques like `String.fromCharCode` with hex decoding and incremental evaluation to build its functionality. The primary intent appears to be downloading and executing a second-stage payload, as indicated by the 'PDF_JS_OBFUSCATED_DROPPER' heuristic. ClamAV also detected this file as 'Pdf.Exploit.Agent-35901'.

Heuristics 7

ClamAV: Pdf.Exploit.Agent-35901 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Pdf.Exploit.Agent-35901
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` `4718a27c2224fc36bf24f8e8e04598f1ad78adce4401c7be2708318738a6983d`	pdf-javascript-stream	PDF /JS object 5 at offset 0x148	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` `c9d99e8145182bbb43d17654e67bc1bc7c45af1753fb1f280c80e96dea6346d9`	deobfuscated-js	repeated-marker hex decoded JavaScript at offset 0x1C1A	1663 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 eval/decoder/string-building token(s).
`deobfuscated.js` `ab9899f90d93bf73f759dc3f37fa0f6ffdcd1dadbd5ae94d84e540da5542ed5f`	deobfuscated-js	PDF JavaScript deobfuscation pass	26772 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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