Off-by-one error in Bash - CVE-2014-7187
Published: January 24, 2017 / Updated: March 11, 2017
Vulnerability identifier: #VU5328
CSH Severity: Critical
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:A/U:Red
CVE-ID: CVE-2014-7187
CWE-ID: CWE-193
Exploitation vector: Remote access
Exploit availability:
Public exploit is available
Vendor: GNU
Affected software:
Bash
Bash
Detailed vulnerability description
The vulnerability allows a remote attacker to execute arbitrary code on the target system.
The weakness exists due to off-by-one-error when handling deeply nested flow control constructs. A remote attacker can trigger memory corruption and execute arbitrary code with privileges of the current user.
Exploitation example:
(for x in {1..200} ; do echo "for x$x in ; do :"; done; for x in {1..200} ; do echo done ; done) | bash ||
echo "CVE-2014-7187 vulnerable, word_lineno"
Successful exploitation results in arbitrary code execution on the vulnerable system.
Note: this vulnerability was being actively exploited.
How to mitigate CVE-2014-7187
Update GNU Bash to version 4.3 bash43-027.