CVE-2011-4862
Description
From CVE.org
Buffer overflow in libtelnet/encrypt.c in telnetd in FreeBSD 7.3 through 9.0, MIT Kerberos Version 5 Applications (aka krb5-appl) 1.0.2 and earlier, Heimdal 1.5.1 and earlier, GNU inetutils, and possibly other products allows remote attackers to execute arbitrary code via a long encryption key, as exploited in the wild in December 2011.
Statement
A buffer overflow flaw was found in the MIT krb5 telnet daemon (telnetd) as shipped with all supported versions of Red Hat Enterprise Linux. A remote attacker who can access the telnet port of a target machine could use this flaw to execute arbitrary code as root.
While we are aware of public exploits for this issue that include targets for Red Hat Enterprise Linux 3, we are not aware of any yet which would be successful in gaining arbitrary root code execution in Red Hat Enterprise Linux 4, 5, or 6. However it is plausible that one could be created to do so.
Note that the krb5 telnet daemon is not enabled by default in any version of Red Hat Enterprise Linux. In addition, the default firewall rules block remote access to the telnet port. This flaw does not affect the telnet daemon distributed in the telnet-server package.
For users who have enabled the krb5 telnet daemon and have it accessible remotely, they should disable it or apply the updates we have released.
Since same encryption code is shared between the MIT krb5 telnet daemon and the telnet client, this issue affects the telnet client as well. The updates we have released fixes the issue for both, the telnet daemon and the telnet client.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v2 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 8.3 | 10 | N/A |
| Attack Vector | Adjacent Network | Network | N/A |
| Access Complexity | Low | Low | N/A |
| Authentication | None | None | N/A |
| Confidentiality Impact | Complete | Complete | N/A |
| Integrity Impact | Complete | Complete | N/A |
| Availability Impact | Complete | Complete | N/A |
Vector
Red Hat: AV:A/AC:L/Au:N/C:C/I:C/A:C
NVD: AV:N/AC:L/Au:N/C:C/I:C/A:C
Understanding the Weakness (CWE)
Integrity,Availability,Confidentiality
Technical Impact: DoS: Crash, Exit, or Restart; Execute Unauthorized Code or Commands; Read Memory; Modify Memory
If the incorrect calculation is used in the context of memory allocation, then the software may create a buffer that is smaller or larger than expected. If the allocated buffer is smaller than expected, this could lead to an out-of-bounds read or write (CWE-119), possibly causing a crash, allowing arbitrary code execution, or exposing sensitive data.
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