CVE-2018-1000030
Description
From CVE.org
Python 2.7.14 is vulnerable to a Heap-Buffer-Overflow as well as a Heap-Use-After-Free. Python versions prior to 2.7.14 may also be vulnerable and it appears that Python 2.7.17 and prior may also be vulnerable however this has not been confirmed. The vulnerability lies when multiply threads are handling large amounts of data. In both cases there is essentially a race condition that occurs. For the Heap-Buffer-Overflow, Thread 2 is creating the size for a buffer, but Thread1 is already writing to the buffer without knowing how much to write. So when a large amount of data is being processed, it is very easy to cause memory corruption using a Heap-Buffer-Overflow. As for the Use-After-Free, Thread3->Malloc->Thread1->Free's->Thread2-Re-uses-Free'd Memory. The PSRT has stated that this is not a security vulnerability due to the fact that the attacker must be able to run code, however in some situations, such as function as a service, this vulnerability can potentially be used by an attacker to violate a trust boundary, as such the DWF feels this issue deserves a CVE.
Statement
Versions of Python 2 included in Red Hat Enterprise Linux 6 and 7 are affected by this issue. Reading concurrently from the same file handle in multiple threads is inherently unstable, and should not be relied upon in any real program. This issue is not planned to be fixed in future releases.
This CVE assignment was disputed by upstream. While an attack is theoretically possible, it relies on a programming pattern in the vulnerable Python program that is generally considered bad practice if not an outright bug.
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).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 3.6 | 3.6 | 3.6 |
| Attack Vector | Local | Local | Local |
| Attack Complexity | High | High | High |
| Privileges Required | Low | Low | Low |
| User Interaction | None | None | None |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | Low | Low | Low |
| Integrity Impact | None | None | None |
| Availability Impact | Low | Low | Low |
Vector
Red Hat: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:L
NVD: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:L
cve.org: CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:L
Red Hat CVSS v3 Score Explanation
This flaw requires special conditions to trigger: a crafted file on the local filesystem and sufficient influence on the running program to cause concurrent reads, in multiple threads, of the same file (AV:L/PR:L).
Precise control of how this flaw manifests in an attack scenario is virtually impossible. Combined with compiler mitigations used on Red Hat Enterprise Linux, the impact is limited to C:L/I:N/A:L.
Understanding the Weakness (CWE)
Integrity,Other
Technical Impact: Alter Execution Logic; Unexpected State
The main problem is that -- if a lock is overcome -- data could be altered in a bad state.
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