PDF malware analysis — malicious · fb3f17669688a71a

MALICIOUS

PDF

8.2 KB

MD5: 9b8e6ad9f7b390ee3f64294c7da2e445 SHA-1: 58fc9f520fde90c1e95ee98c0c2e14371b2569bb SHA-256: fb3f17669688a71aa47d9c4d90d3274fcd21659e0f1191aa4d83170f2c86535b

256 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell T1204.001 Malicious Link T1071.001 Web Protocols

The PDF file contains obfuscated JavaScript that leverages the CVE-2007-5659 vulnerability through the `collab.collectEmailInfo` function. The JavaScript is designed as a multi-stage dropper, indicated by the `PDF_JS_OBFUSCATED_DROPPER` heuristic and the presence of multiple deobfuscated JavaScript files. The script likely downloads and executes a second-stage payload, as suggested by the dropper nature and the ML classifier's high confidence score. No specific IOCs like URLs or hashes were extracted, but the exploit primitive and dropper behavior are clear.

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` `6c13b101cfcf44b5e3d395ef6397eabfbaa0fc602c639dbab37208210c387d5d`	deobfuscated-js	repeated-marker hex decoded JavaScript at offset 0x1B52	1847 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` `81e3962aa91e77342d8d9e003d5625c6bdca2cf6c9d21fa7b564c1431ae042ee`	deobfuscated-js	annotation-subject callee-key decoded JavaScript at offset 0x329	5072 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 5 eval/decoder/string-building token(s).
`deobfuscated.js` `b60543ece8bd8d8ab1c2f25469add9818c08f51459e4843b565ba548f04b9df0`	deobfuscated-js	PDF JavaScript deobfuscation pass	23253 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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