Malware Insights
The PDF file contains embedded JavaScript that utilizes eval() and String.fromCharCode() functions. This JavaScript is heavily obfuscated and appears to implement a custom Base64 decoder to unwrap multiple layers of encoded content. The primary exploit targets are CVE-2009-0927 (Collab.getIcon), CVE-2007-5659 (Collab.collectEmailInfo), and CVE-2008-2992 (util.printf), indicating an attempt to exploit Adobe Reader vulnerabilities. The extracted artifact 'custom_b64_stage_000.js' was detected by ClamAV as 'Js.Exploit.Shellcode-18', confirming the malicious nature of the embedded script which likely downloads and executes a second-stage payload.
Heuristics 10
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Collab.getIcon — CVE-2009-0927 critical CVE exact CVE_2009_0927PDF JavaScript calls Collab.getIcon — CVE-2009-0927 is a stack buffer overflow in Adobe Reader triggered by Collab.getIcon() with a crafted argument. Allows arbitrary code execution. (identified after JavaScript deobfuscation)
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Collab.collectEmailInfo — CVE-2007-5659 critical CVE exact CVE_2007_5659PDF 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)
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util.printf — CVE-2008-2992 critical CVE exact CVE_2008_2992PDF JavaScript calls util.printf() — CVE-2008-2992 is a stack buffer overflow in Adobe Reader triggered by a long format-specifier argument. Widely exploited in the wild after disclosure. (identified after JavaScript deobfuscation)
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ClamAV detection on extracted artifact critical EXTRACTED_FILE_CLAMAVClamAV flagged at least one file extracted from inside this sample. Even when the wrapping document carries no AV detection of its own, a hit on the carved artifact is a strong indicator the sample is a delivery vehicle.
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OpenAction trigger high PDF_OPENACTIONPDF has an /OpenAction — code runs automatically when opened
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eval() call high PDF_EVALeval() found — commonly used for obfuscated exploit execution (matched inside decoded stream)
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JavaScript action low PDF_JAVASCRIPTPDF contains a /JavaScript action. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
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Embedded JS stream low PDF_JSPDF references a /JS stream. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
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String.fromCharCode low PDF_FROMCHARCODEString.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)
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Suspicious extracted artifact info EXTRACTED_FILE_STATIC_TRIAGEOne 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 2
Files carved from inside the sample during analysis.
| Filename | Kind | Source | Size |
|---|---|---|---|
javascript_obj0009_000.jsa8f158eaea0f9c5c1695b575f683e0d0bf6097f7c878e297a348cede49460ed0 |
pdf-javascript-stream | PDF /JS object 9 at offset 0xD6 | 19488 bytes |
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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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custom_b64_stage_000.jsa4d46ddebde70715566a34570775ebf1451e8498d4fc53b92d9f605d56fb05f5 |
deobfuscated-js | custom Base64 decoded JavaScript layer 2 (PDF /JS object 9) at offset 0x436 | 10455 bytes |
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Detection
ClamAV:
Js.Exploit.Shellcode-18
Obfuscation or payload:
likely
Carved artifact contains 9 eval/decoder/string-building token(s).
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