A vulnerability in Snort, the popular open-source intrusion protection software, could <A HREF="http://news.zdnet.com/2100-1009_22-5900502.html?tag=zdnn.alert">open networks to cyberattack.</A> A buffer overflow flaw exists in a Snort sensor designed to detect Back Orifice, an older remote-controlled Trojan horse, Snort developer Sourcefire said in an advisory on Tuesday. An attacker could commandeer a system running Snort 2.4.0 and higher by sending a specially crafted network packet, it warned. Sourcefire's warning prompted security provider Symantec to raise its ThreatCon global threat index to Level 2, which means an outbreak is expected.