A certain pseudo-random number generator (PRNG) algorithm that uses XOR and 3-bit random hops (aka "Algorithm X3"), as used in OpenBSD 2.8 through 4.2, allows remote attackers to guess sensitive values such as DNS transaction IDs by observing a sequence of previously generated values. NOTE: this issue can be leveraged for attacks such as DNS cache poisoning against OpenBSD's modification of BIND.

References

• https://nvd.nist.gov/vuln/detail/CVE-2008-1146
• https://exchange.xforce.ibmcloud.com/vulnerabilities/40329
• http://secunia.com/advisories/28819
• http://www.securiteam.com/securityreviews/5PP0H0UNGW.html
• http://www.securityfocus.com/archive/1/487658
• http://www.securityfocus.com/bid/27647
• http://www.trusteer.com/docs/OpenBSD_DNS_Cache_Poisoning_and_Multiple_OS_Predictable_IP_ID_Vulnerability.pdf