PDF malware analysis — malicious · 9138b7c40023b7a4

MALICIOUS

PDF

8.2 KB

MD5: 21ce6d7daa970dcac4d48010d11ee3cb SHA-1: 4f7f95937d7dd928804e00b7d131502673bf3321 SHA-256: 9138b7c40023b7a41c10c25161fbcc06fbf94f602b8f21bdda5967f7368b9503

258 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 JavaScript T1204.002 Malicious Link

The PDF sample contains obfuscated JavaScript, indicated by multiple heuristic firings including 'PDF_JAVASCRIPT', 'PDF_JS_OBFUSCATED_DROPPER', and 'PDF_UNESCAPE'. The critical 'CVE_2007_5659' firing points to the exploitation of a known PDF vulnerability. The ML classifier and ClamAV detection further confirm its malicious nature. The primary attack vector involves leveraging the 'Collab.collectEmailInfo' function to decode and execute embedded JavaScript, likely to download and run a secondary payload.

Machine Learning

Nyx PDF Classifier malicious score 1.0000

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-36086 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Pdf.Exploit.Agent-36086
unescape() call high PDF_UNESCAPE

unescape() found — often used to decode shellcode in PDF JS exploits (matched inside decoded stream)
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, 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.
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_obj0006_000.js` `f9b4659beaf681d266cfb5046d495e7b144d406eff72e71ecd4d1451ae25ca11`	pdf-javascript-stream	PDF /JS object 6 at offset 0x143	481 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` `6616f26f8f36ac4bcc137c6500b58b7ee3768ba1624a22bbae523d4b8b4c7a16`	deobfuscated-js	repeated-marker hex decoded JavaScript at offset 0x1B6B	1804 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 2 eval/decoder/string-building token(s).
`legacy_pdfkit_stage_001.js` `2f1f179abaddd34f53262e14232f256e630a49a4c6e3787b047bd3b686f464c9`	deobfuscated-js	annotation-subject callee-key decoded JavaScript at offset 0x329	5142 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 5 eval/decoder/string-building token(s).
`deobfuscated.js` `dbbd365fba5f8a713a1895e0a673f7a4105bff0939fb9e01e8a33397dce5a366`	deobfuscated-js	PDF JavaScript deobfuscation pass	24583 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 4 eval/decoder/string-building token(s). Carved artifact contains 2 long base64-like blob(s).

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