CVE-2012-6711
Description
A heap-based buffer overflow was discovered in bash when wide characters, not supported by the current locale set in LC_CTYPE environment variable, are printed through the echo built-in function. A local attacker, who can provide data to print through the echo -e built-in function, may use this flaw to crash a script or execute code with the privileges of the bash process.
Statement
Impact set to Moderate as the flaw requires the usage of echo -e built-in function with a string controlled by the attacker. Abusing this flaw would allow an attacker to, at most, execute code with the privileges of the bash process, which could be used e.g. to escape a restricted shell in case of a local attacker scenario or remotely execute code in case of a bash script that accepts untrusted input from the network. However we do not recommend to use bash scripts to handle untrusted data from the network.
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 | 7 | 7.8 | N/A |
| Attack Vector | Local | Local | N/A |
| Attack Complexity | High | 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:H/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Red Hat CVSS v3 Score Explanation
Attack Complexity (AC) set to High (H) as the flaw requires the use the echo built-in function with the -e option, which allows you to print unicode characters given the right bytes values, and an attacker controlled string passed as input. Moreover, mitigations such as ASLR are in place, making a full attack harder.
Acknowledgements
Red Hat would like to thank Erez Turjeman for reporting this issue.
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