CVE-2015-0240
Description
An uninitialized pointer use flaw was found in the Samba daemon (smbd). A malicious Samba client could send specially crafted netlogon packets that, when processed by smbd, could potentially lead to arbitrary code execution with the privileges of the user running smbd (by default, the root user).
Statement
This issue does not affect the version of samba package as shipped with Red Hat Enterprise Linux 4 and 5. It does affect the version of samba as shipped with Red Hat Enterprise Linux 6 and 7, as well as the version of samba3x shipped with Red Hat Enterprise Linux 5 and the version of samba4 as shipped with Red Hat Enterprise Linux 6.
Red Hat Product Security has determined that this vulnerability has Important impact on Red Hat Enterprise Linux 7 because the Samba version shipped in this version of the operating system only executes the vulnerable code after a memory allocation failure, making it more difficult to exploit this flaw.
Mitigation
On Samba versions 4.0.0 and above, add the line:
rpc_server:netlogon=disabled
to the [global] section of your smb.conf. For Samba versions 3.6.x and
earlier, this workaround is not available.
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 | 7.9 | 10 | N/A |
| Attack Vector | Adjacent Network | Network | N/A |
| Access Complexity | Medium | 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:M/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,Confidentiality,Availability
Technical Impact: Execute Unauthorized Code or Commands; Modify Memory
If the memory accessible by the attacker can be effectively controlled, it may be possible to execute arbitrary code, as with a standard buffer overflow. If the attacker can overwrite a pointer's worth of memory (usually 32 or 64 bits), they can alter the intended control flow by redirecting a function pointer to their own malicious code. Even when the attacker can only modify a single byte arbitrary code execution can be possible. Sometimes this is because the same problem can be exploited repeatedly to the same effect. Other times it is because the attacker can overwrite security-critical application-specific data -- such as a flag indicating whether the user is an administrator.
Availability,Confidentiality
Technical Impact: Read Memory; DoS: Crash, Exit, or Restart; DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory)
Out of bounds memory access will very likely result in the corruption of relevant memory, and perhaps instructions, possibly leading to a crash. Other attacks leading to lack of availability are possible, including putting the program into an infinite loop.
Confidentiality
Technical Impact: Read Memory
In the case of an out-of-bounds read, the attacker may have access to sensitive information. If the sensitive information contains system details, such as the current buffer's position in memory, this knowledge can be used to craft further attacks, possibly with more severe consequences.
Acknowledgements
Red Hat would like to thank Samba project for reporting this issue. Upstream acknowledges Richard van Eeden (Microsoft Vulnerability Research) as the original reporter.
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