Malicious PDF — malware analysis report

Static analysis result for SHA-256 1126b9220e267516…

MALICIOUS

PDF

44.7 KB
MD5: 130c6f07e44d9c384405faaaf52acf90 SHA-1: 6fe75d28a7584e846adf1a03ad5cfa0f15e8109f SHA-256: 1126b9220e26751639885a03ea80c2459d302acd5c3c0ebf8444b436593187db
336 Risk Score

Malware Insights

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

The PDF file exploits CVE-2010-2883, a known Adobe Reader vulnerability, to execute embedded JavaScript. This JavaScript is designed to download and execute a second-stage payload from the URL http://fasted.in/nte/koha.php/yHffdf40e4V0100f070006R59e915ca102Tb365dda2201l0409327. The critical heuristic firings and ML classification strongly indicate malicious intent.

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://fasted.in/nte/koha.php/yHffdf40e4V0100f070006R59e915ca102Tb365dda2201l0409327
    • 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
4e8b35ff990cd3f6f1520555843b10c74ea4100094acac9d336449d600bbc0f3		 pdf-javascript-stream PDF /JS object 12 at offset 0xA0BA 3688 bytes
javascript_obj0012_001.js
5eafb0b7681a3a06ed61e91a4b180392d8a6fc9d1dac127c0498d3f2a2e16b08		 pdf-javascript-stream PDF /JS object 12 at offset 0xA100 4574 bytes
generic_stage_recovery_000.js
958387a1697c4cd60e52acaf0a6a9f2b705b5ab285fbbf99f6e9d8fe2e014c17		 deobfuscated-js generic stage recovery split-literal-normalize from JavaScript object 12 at offset 0xA0BA 3638 bytes
generic_stage_recovery_001.js
026516a910a287e93ddc9f549d2baaef686018836fbb972eddb1ea674cc063c3		 deobfuscated-js generic stage recovery split-literal-normalize from JavaScript object 12 at offset 0xA100 4524 bytes
generic_stage_recovery_002.js
42cba2f6066de81b8305c1da5a2714f38ebdacaf04b2a21233def7aaa6d3085a		 deobfuscated-js generic stage recovery split-literal-normalize from combined JavaScript objects at offset 0xA0BA 8163 bytes
Detection
ClamAV: Js.Exploit.Shellcode-18
Obfuscation or payload: unlikely
generic_stage_recovery_003.js
d6ef13bd44a85155485f732ebc808ff67150ee4664e71c96f99cf8de81ec7978		 deobfuscated-js generic stage recovery split-literal-normalize from decompressed stream at 0x0 at offset 0x0 45738 bytes
generic_stage_recovery_004.js
a28f1bc7f576748086148c12d2e1abfec3cebf96b75fc5506cfde26016f6e074		 deobfuscated-js generic stage recovery percent-decode from decompressed stream at 0x0 at offset 0x0 45786 bytes
generic_stage_recovery_005.js
3d6b30bb2bb7cac03e6441691b8de5010e06bcfd1b7e8806e615c8c380f0d5e2		 deobfuscated-js generic stage recovery split-literal-normalize -> percent-decode from decompressed stream at 0x0 at offset 0x0 45736 bytes
font_00_sfnt_off0000033c.bin
683fcffe9abaad29001e134bdd9ad7d1628d5cbbf628c451b6c621f202a7dae4		 pdf-font-stream PDF embedded font (sfnt) at offset 0x33C 65932 bytes

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