Malicious PDF — malware analysis report

Static analysis result for SHA-256 5f2a77e4e414e406…

MALICIOUS

PDF

44.7 KB
MD5: 425f755ccf2340da7237eb158d346868 SHA-1: 6a8d015c16ada807f118ffecbe14a1c6e416a61e SHA-256: 5f2a77e4e414e406483b34911c3864094fd148189412aeb009184be1809a17ed
336 Risk Score

Malware Insights

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

The PDF contains JavaScript that exploits CVE-2010-2883, a known Adobe Reader vulnerability. The embedded JavaScript includes a URL, http://belisimo.in/nte/koha.html/yHe5fbf50bV0100f070006Rd6bb454510aTa94da3e2201l0409327, which is likely used to download and execute a secondary payload. ClamAV also detected a shellcode exploit within an extracted artifact.

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://belisimo.in/nte/koha.html/yHe5fbf50bV0100f070006Rd6bb454510aTa94da3e2201l0409327
    • 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
2b94e1d5c6644b1fec48e85dc4e7e3f4b774403ec0f8bc46b12cd0fbb5913ecf		 pdf-javascript-stream PDF /JS object 12 at offset 0xA0BA 3700 bytes
javascript_obj0012_001.js
516aa548b44ca0022b8bfaaabcd0c74b93c3d8ab7a36d41b40bbcb0982423af8		 pdf-javascript-stream PDF /JS object 12 at offset 0xA100 4586 bytes
generic_stage_recovery_000.js
bbfb203b7bb11367e191d3173c7b3e4471216728e7106a1a0db5875ca18a8cdc		 deobfuscated-js generic stage recovery split-literal-normalize from JavaScript object 12 at offset 0xA0BA 3650 bytes
generic_stage_recovery_001.js
b6aa5a05ac766cc3d6af3235752479c91c6a7b10b42518d0b8bc39cf278957f4		 deobfuscated-js generic stage recovery split-literal-normalize from JavaScript object 12 at offset 0xA100 4536 bytes
generic_stage_recovery_002.js
e0f76b14edc91105add9b66a0beabf0649d47ea5ca01a0ac2da27e4a3da8096d		 deobfuscated-js generic stage recovery split-literal-normalize from combined JavaScript objects at offset 0xA0BA 8187 bytes
Detection
ClamAV: Js.Exploit.Shellcode-18
Obfuscation or payload: unlikely
generic_stage_recovery_003.js
4d5788b56c996bba65f808b62122439b71e8f3204344ccc5669b2f9de3f39a0b		 deobfuscated-js generic stage recovery split-literal-normalize from decompressed stream at 0x0 at offset 0x0 45750 bytes
generic_stage_recovery_004.js
5a864255fd4d2b56f615c0016ad53a37e4bf5b7a3e8eefdb18d8b55700b3972b		 deobfuscated-js generic stage recovery percent-decode from decompressed stream at 0x0 at offset 0x0 45798 bytes
generic_stage_recovery_005.js
54316f336e106e73b07078e338e9f75c90991f776a71d4c442eed7aa7f59434e		 deobfuscated-js generic stage recovery split-literal-normalize -> percent-decode from decompressed stream at 0x0 at offset 0x0 45748 bytes
font_00_sfnt_off0000033c.bin
683fcffe9abaad29001e134bdd9ad7d1628d5cbbf628c451b6c621f202a7dae4		 pdf-font-stream PDF embedded font (sfnt) at offset 0x33C 65932 bytes

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