Malicious PDF — malware analysis report

Static analysis result for SHA-256 657d377f72a628d2…

MALICIOUS

PDF

44.8 KB
MD5: bcf62575e2277618e384d4055b50685c SHA-1: 75cc7f06fd4e0965aeeb8b8082329ce94b765f28 SHA-256: 657d377f72a628d205b94bcd4b81b61002b828aede020ff52430968829f855ec
336 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1059.007 JavaScript

The PDF file contains embedded JavaScript that exploits CVE-2010-2883, a known vulnerability in Adobe Reader. The JavaScript is designed to download a second-stage payload from the URL http://afreelis.net/nte/AVORP1VENA.py/yUd1cf61ceHa6cd5c9bV0100f080006Rd709609c10aTea789a9f201l000a327. This behavior is consistent with a downloader or initial access exploit.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9999

Heuristics 10

  • Adobe Reader CoolType SING font exploit — CVE-2010-2883 critical CVE likely CVE_2010_2883
    PDF embeds a TrueType/OpenType font with an actual SING table and pairs it with JavaScript heap-spray shellcode. This matches the public Adobe Reader CoolType SING exploit shape for CVE-2010-2883.
  • 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 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.
  • Generic recovered JavaScript exploit stage high PDF_GENERIC_STAGE_RECOVERY
    Bounded static stage recovery exposed hidden JavaScript through generic transforms such as null-byte collapse, percent decoding, marker replacement, arithmetic character codes, fromCharCode, numeric arrays, numeric-array minus-key decoders, alphabet-index arrays, /Producer half-difference metadata arrays, hex literals, marker-stripped Base64 literals, custom 6-bit XOR table decoders, or repeated-marker hex carriers. This rule is emitted only when the recovered stage contains exploit-like Acrobat JavaScript or shellcode markers.
  • 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).
  • ASCIIHexDecode filter (with exploit indicators) medium PDF_FILTER_HEX
    Hex-encoding filter present alongside exploit delivery indicators — often used to hide payload or shellcode bytes
  • 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.
  • XFA form low PDF_XFA
    PDF uses XML Forms Architecture — can contain script logic
  • 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://afreelis.net/nte/AVORP1VENA.py/yUd1cf61ceHa6cd5c9bV0100f080006Rd709609c10aTea789a9f201l000a327
    • http://www.bitstream.com
    • http://ns.adobe.com/xdp/
    • http://www.xfa.org/schema/xci/2.6/
    • http://www.xfa.org/schema/xfa-template/2.6/

Extracted artifacts 9

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0012_000.js
316565dc6a2065a579ca35d4aa1b476f51ad91933eba489d11e2b985df15eb3b		 pdf-javascript-stream PDF /JS object 12 at offset 0xA0BA 3730 bytes
javascript_obj0012_001.js
a9552a7efe78ac3bad237aab78b204287af2766c344c43f9ad7839219e39e160		 pdf-javascript-stream PDF /JS object 12 at offset 0xA100 4616 bytes
generic_stage_recovery_000.js
08666639f3f74229609e0e1a5e10c78fca86c18774f23b94e542f747b86f2f88		 deobfuscated-js generic stage recovery split-literal-normalize from JavaScript object 12 at offset 0xA0BA 3680 bytes
generic_stage_recovery_001.js
28195701af250a89c885ce305d5b2513cac7d4c4d28306114e7bd2f3951dbcda		 deobfuscated-js generic stage recovery split-literal-normalize from JavaScript object 12 at offset 0xA100 4566 bytes
generic_stage_recovery_002.js
353d6f0e68b62625d967be4e8e1122358e6de19c2557e0c2f8f37232c960eba4		 deobfuscated-js generic stage recovery split-literal-normalize from combined JavaScript objects at offset 0xA0BA 8247 bytes
Detection
ClamAV: Js.Exploit.Shellcode-18
Obfuscation or payload: unlikely
generic_stage_recovery_003.js
249ae806b94f5b11335556800591d69782efb9c73539a68b75229264af14ef14		 deobfuscated-js generic stage recovery split-literal-normalize from decompressed stream at 0x0 at offset 0x0 45780 bytes
generic_stage_recovery_004.js
34139c35d9b849ed30fdc5c806cae6be000b42a1cfe9f5b6f9c53e427495842b		 deobfuscated-js generic stage recovery percent-decode from decompressed stream at 0x0 at offset 0x0 45828 bytes
generic_stage_recovery_005.js
1ca97ae4284924ee0a71514db8ec3214b22077ad70e072e8963908e68d9ac35d		 deobfuscated-js generic stage recovery split-literal-normalize -> percent-decode from decompressed stream at 0x0 at offset 0x0 45778 bytes
font_00_sfnt_off0000033c.bin
683fcffe9abaad29001e134bdd9ad7d1628d5cbbf628c451b6c621f202a7dae4		 pdf-font-stream PDF embedded font (sfnt) at offset 0x33C 65932 bytes

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