PDF malware analysis — malicious · 603bfc88ebf002bf

MALICIOUS

PDF

2.6 KB Created: 2008-08-06 01:42:27 Authoring application: Scribus 1.3.3.12 (via Scribus PDF Library 1.3.3.12)

MD5: 220e84ba5748fbd62234f3f8db52c660 SHA-1: ef58f9a70a1394a275868be70b18afc03d2e90cc SHA-256: 603bfc88ebf002bf213ddae4f465f470858da28fe3e848016359b639d9288c8e

370 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1059.007 JavaScript

The PDF file contains embedded JavaScript that exploits CVE-2007-5659 (Collab.collectEmailInfo) and uses unescape() to decode shellcode. This shellcode contains a URL, http://onlinestat.cn/forum/file3.exe, which is likely used to download and execute a second-stage payload. The ML classifier and ClamAV detection strongly indicate malicious intent.

Machine Learning

Nyx PDF Classifier malicious score 1.0000

Heuristics 10

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. (matched in decompressed stream)
PDF JavaScript exploit cluster critical PDF_JS_EXPLOIT_CLUSTER

PDF combines an executable JavaScript/action surface with exploit staging indicators such as eval/unescape/fromCharCode, XFA script content, or a related CVE pattern. Benign form JavaScript remains low-severity, but this correlated cluster is high-confidence malicious behavior.
ClamAV: Pdf.Exploit.Agent-34662 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Pdf.Exploit.Agent-34662
ClamAV detection on extracted artifact critical EXTRACTED_FILE_CLAMAV

ClamAV 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.
unescape() call high PDF_UNESCAPE

unescape() found — often used to decode shellcode in PDF JS exploits (matched inside decoded stream)
PDF JavaScript shellcode contains an embedded download URL high PDF_JS_SHELLCODE_DOWNLOAD_URL

Decoded PDF JavaScript shellcode contains a hardcoded http(s) URL stored as little-endian %uXXXX Unicode escapes. Reader exploit shellcode embeds the second-stage fetch URL this way and pulls it down with a urlmon/URLDownloadToFile-style download-and-execute (commodity downloader behaviour rather than a specific Acrobat CVE).
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.
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.
Embedded URL info EMBEDDED_URL

One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.

URL http://onlinestat.cn/forum/file3.exe

Extracted artifacts 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0013_001.js` `f2545365baf05d6d793a5a4bc7404779fbdc4318b4bca47a0d8b572c74d9e7ff`	pdf-javascript-stream	PDF /JS object 13 at offset 0x39D	2606 bytes
Detection ClamAV: Pdf.Exploit.Agent-34662 Obfuscation or payload: likely Carved artifact contains 3 eval/decoder/string-building token(s).
`combined_document_js_000.js` `b08f7c446c2ebf6a6e426f75ba1d27cf292318818a995f5dd9fa3b2320ae433e`	deobfuscated-js	combined document JavaScript streams at offset 0xF	2630 bytes
Detection ClamAV: Pdf.Exploit.Agent-34662 Obfuscation or payload: likely Carved artifact contains 3 eval/decoder/string-building token(s).

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