Security Advisory-Bash Code Injection Vulnerability

This security advisory (SA) describes the impact of 6 Bash vulnerabilities discovered in third-party software (Vulnerability ID: HWPSIRT-2014-0951).

1.OS Command Injections vulnerability (CVE-2014-6271). GNU Bash through 4.3 processes trailing strings after function definitions in the values of environment variables, which allows remote attackers to execute arbitrary code via a crafted environment, as demonstrated by vectors involving the ForceCommand feature in OpenSSH sshd, the mod_cgi and mod_cgid modules in the Apache HTTP Server, scripts executed by unspecified DHCP clients, and other situations in which setting the environment occurs across a privilege boundary from Bash execution, aka “ShellShock.” NOTE: the original fix for this issue was incorrect; CVE-2014-7169 has been assigned to cover the vulnerability that is still present after the incorrect fix.

The NVD link is: <http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2014-6271&gt;

2.OS Command Injections vulnerability (CVE-2014-6277). GNU Bash through 4.3 bash43-026 does not properly parse function definitions in the values of environment variables, which allows remote attackers to execute arbitrary code or cause a denial of service (uninitialized memory access, and untrusted-pointer read and write operations) via a crafted environment, as demonstrated by vectors involving the ForceCommand feature in OpenSSH sshd, the mod_cgi and mod_cgid modules in the Apache HTTP Server, scripts executed by unspecified DHCP clients, and other situations in which setting the environment occurs across a privilege boundary from Bash execution. NOTE: this vulnerability exists because of an incomplete fix for CVE-2014-6271 and CVE-2014-7169.

The NVD link is: <http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2014-6277&gt;

3.OS Command Injections vulnerability (CVE-2014-6278). GNU Bash through 4.3 bash43-026 does not properly parse function definitions in the values of environment variables, which allows remote attackers to execute arbitrary commands via a crafted environment, as demonstrated by vectors involving the ForceCommand feature in OpenSSH sshd, the mod_cgi and mod_cgid modules in the Apache HTTP Server, scripts executed by unspecified DHCP clients, and other situations in which setting the environment occurs across a privilege boundary from Bash execution. NOTE: this vulnerability exists because of an incomplete fix for CVE-2014-6271, CVE-2014-7169, and CVE-2014-6277.

The NVD link is: <http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2014-6278&gt;

4.OS Command Injections vulnerability (CVE-2014-7169). GNU Bash through 4.3 bash43-025 processes trailing strings after certain malformed function definitions in the values of environment variables, which allows remote attackers to write to files or possibly have unknown other impact via a crafted environment, as demonstrated by vectors involving the ForceCommand feature in OpenSSH sshd, the mod_cgi and mod_cgid modules in the Apache HTTP Server, scripts executed by unspecified DHCP clients, and other situations in which setting the environment occurs across a privilege boundary from Bash execution. NOTE: this vulnerability exists because of an incomplete fix for CVE-2014-6271.

The NVD link is: <http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2014-7169&gt;

5.OS Command Injections vulnerability (CVE-2014-7186). The redirection implementation in parse.y in GNU Bash through 4.3 bash43-026 allows remote attackers to cause a denial of service (out-of-bounds array access and application crash) or possibly have unspecified other impact via crafted use of here documents, aka the “redir_stack” issue.

The NVD link is: <http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2014-7186&gt;

6.OS Command Injections vulnerability (CVE-2014-7187). Off-by-one error in the read_token_word function in parse.y in GNU Bash through 4.3 bash43-026 allows remote attackers to cause a denial of service (out-of-bounds array access and application crash) or possibly have unspecified other impact via deeply nested for loops, aka the “word_lineno” issue.
The NVD link is: <http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2014-7187&gt;