CVE-2017-7184
Description
Out-of-bounds kernel heap access vulnerability was found in xfrm, kernel's IP framework for transforming packets. An error dealing with netlink messages from an unprivileged user leads to arbitrary read/write and privilege escalation.
Statement
This issue does not affect the Linux kernel packages as shipped with Red Hat Enterprise Linux 5, 6 as the code with the flaw is not present in the products listed.
This issue affects the Linux kernel packages as shipped with Red Hat Enterprise Linux 7 and MRG-2. In a default or common use of Red Hat Enterprise Linux 7 and MRG-2 this issue does not allow an unprivileged local or remote user to elevate their privileges on the system.
In order to exploit this issue the attacker needs CAP_NET_ADMIN capability, which needs to be granted especially by the administrator to the attacker's process. This in turn requires granting CAP_NET_ADMIN capability to the process' binary and/or attacker's account.
Another possibility to obtain CAP_NET_ADMIN capability in Red Hat Enterprise Linux 7 for an attacker is running a process inside a user+network namespace with mapped root privileges inside the namespace. Since Red Hat Enterprise Linux 7 does not have unprivileged user namespaces enabled by default, local or remote unprivileged users also cannot abuse namespaces to grant this capability to themselves and elevate their privileges.
Given the severity of this issue, future Linux kernel updates for the Red Hat Enterprise Linux 7 and MRG-2 products are planned to address it.
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 v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.8 | 7.8 | N/A |
| Attack Vector | Local | Local | N/A |
| Attack Complexity | Low | Low | N/A |
| Privileges Required | Low | Low | N/A |
| User Interaction | None | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | High | High | N/A |
| Integrity Impact | High | High | N/A |
| Availability Impact | High | High | N/A |
Vector
Red Hat: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Crash, Exit, or Restart; DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory)
Buffer overflows generally lead to crashes. Other attacks leading to lack of availability are possible, including putting the program into an infinite loop.
Integrity,Confidentiality,Availability,Access Control
Technical Impact: Execute Unauthorized Code or Commands; Bypass Protection Mechanism; Modify Memory
Buffer overflows often can be used to execute arbitrary code, which is usually outside the scope of a program's implicit security policy. Besides important user data, heap-based overflows can be used to overwrite function pointers that may be living in memory, pointing it to the attacker's code. Even in applications that do not explicitly use function pointers, the run-time will usually leave many in memory. For example, object methods in C++ are generally implemented using function pointers. Even in C programs, there is often a global offset table used by the underlying runtime.
Integrity,Confidentiality,Availability,Access Control,Other
Technical Impact: Execute Unauthorized Code or Commands; Bypass Protection Mechanism; Other
When the consequence is arbitrary code execution, this can often be used to subvert any other security service.
Acknowledgements
Red Hat would like to thank Chaitin Security Research Lab for reporting this issue.
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