PDF malware analysis — malicious · e259ba86f0eef656

MALICIOUS

PDF

8.3 KB

MD5: 17ea7d868f1890a7b1a9162f3d74ad05 SHA-1: 2be2c6f7e61a56ca3c6bef4c988aa597392d6d1d SHA-256: e259ba86f0eef65696c5472b3f4008eeb54cf8f1ab4eb0c41716b2e1d5dddcbf

134 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell T1204.001 Malicious Link T1027 Obfuscated Files or Information

The PDF document contains obfuscated JavaScript, identified by the 'PDF_JS_OBFUSCATED_DROPPER' heuristic. This script exploits CVE-2007-5659, leveraging the 'Collab.collectEmailInfo' method to decode and execute a multi-stage payload. The script performs anti-analysis checks by verifying 'app.plugIns.length'. The primary function appears to be downloading and executing a second-stage payload, as indicated by the dropper nature of the heuristics and extracted artifacts.

Heuristics 7

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)
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 4

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0005_000.js` `9d5c7e01faed5b04e9ec11f1d98b73f0012c871beaf60e9f9d32ad6df00d46f7`	pdf-javascript-stream	PDF /JS object 5 at offset 0x148	550 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` `3582c26a501a37f4ad0dda6ad5bd0d8e6e9932818393c497a0ee46a865a5e742`	deobfuscated-js	repeated-marker hex decoded JavaScript at offset 0x1BAF	1849 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` `669626b45e3ebfcf69f19650877465795a83edd7ac2a30d409b73a09c90133d4`	deobfuscated-js	annotation-subject callee-key decoded JavaScript at offset 0x359	5115 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 5 eval/decoder/string-building token(s).
`deobfuscated.js` `a0cf1afeb868a4d7c9cf21a9296ab6b10df0e29ac27f682b840f1f499be05ab2`	deobfuscated-js	PDF JavaScript deobfuscation pass	24347 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 2 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).

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