PDF malware analysis — malicious · 35661e3fb31956e3

MALICIOUS

PDF

8.2 KB

MD5: 77dc4c9b77b2c905fb3e6c6d84728d82 SHA-1: 489632082fa51065b4b7780a007bbd866adfea6a SHA-256: 35661e3fb31956e3e42b5f662c464bd888efc4d80482429f62bbe3308870c9c9

194 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell T1204.002 Malicious File

The PDF sample contains heavily obfuscated JavaScript, indicated by multiple heuristic firings including 'PDF_JS_OBFUSCATED_DROPPER' and 'PDF_FROMCHARCODE'. The critical 'CVE_2007_5659' firing points to the exploitation of a known PDF vulnerability. The embedded JavaScript is designed to download and execute a second-stage payload, as suggested by the 'PDF_JS_OBFUSCATED_DROPPER' heuristic and the presence of multiple deobfuscated JavaScript files. The ClamAV detection further confirms its malicious nature.

Heuristics 8

Collab.collectEmailInfo — CVE-2007-5659 critical CVE exact CVE_2007_5659

PDF JavaScript calls Collab.collectEmailInfo — CVE-2007-5659 is a buffer overflow in Adobe Reader triggered by a long argument or heap-sprayed message field passed to Collab.collectEmailInfo(). Part of a series of Acrobat JS API exploits. (identified after JavaScript deobfuscation)
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 4

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` `9ce8ae9042e66c30bcd248fdc68fee196055cd074f039201fd5c1e9103d78980`	deobfuscated-js	repeated-marker hex decoded JavaScript at offset 0x1B80	1766 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 eval/decoder/string-building token(s).
`legacy_pdfkit_stage_001.js` `e97926046bf5d31b13ad9fde28c39b8ffd6f43c7a07d912616fa6246467cda1c`	deobfuscated-js	annotation-subject callee-key decoded JavaScript at offset 0x352	5085 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 5 eval/decoder/string-building token(s).
`deobfuscated.js` `3edd9cfb521a6dc30fd124fc32338c41b5b57e36a334709e99779062cc928718`	deobfuscated-js	PDF JavaScript deobfuscation pass	25587 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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