PDF malware analysis — malicious · 4e9541d3eedcb777

MALICIOUS

PDF

8.0 KB

MD5: 8601ce0b0d30222e041ae7bebd10e50c SHA-1: 39be50c68d588f29ce89978956999c065b8cf1d7 SHA-256: 4e9541d3eedcb7772c8caa96bed0361f7b1fe992e893684f97e1e5e3708d713b

134 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell T1204.001 Malicious Link T1071.001 Web Protocols T1566.001 Spearphishing Attachment T1204.002 Malicious File

The PDF document contains obfuscated JavaScript, identified as a multi-stage dropper. This script leverages the CVE-2007-5659 vulnerability, specifically using the `Collab.collectEmailInfo` function to execute a decoded payload. The dropper's primary function is to download and execute additional malicious content, indicated by the presence of multiple deobfuscated JavaScript files and heuristic firings related to obfuscated JavaScript droppers. The exact nature of the final payload is not determined from this analysis, but the delivery mechanism is clear.

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` `ab3f4be7a3e2e879e844dcace56ca59cf8fe7249dc5a05c90896f0c9e7dd732a`	pdf-javascript-stream	PDF /JS object 5 at offset 0x148	559 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` `83682c09eab423194b344ee3b7c9baaa55c6062f4ae8a068ba6e4311a4b8aeb1`	deobfuscated-js	repeated-marker hex decoded JavaScript at offset 0x1A92	1823 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` `f84ed226f2dcdd49e0b99b9129f631451263d51d4a4aa44522fdc56ab250f1e9`	deobfuscated-js	annotation-subject callee-key decoded JavaScript at offset 0x374	4855 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 5 eval/decoder/string-building token(s).
`deobfuscated.js` `1d4235fa36b04d46ab224ef3146c2cf315f5522b6351bee2ef0e84a655ceb8b8`	deobfuscated-js	PDF JavaScript deobfuscation pass	42213 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 4 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).

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