CVE-2009-4492
CVE-2009-4492 is a security vulnerability in ruby-lang webrick. 4 public exploit references exist, so weaponization risk is real. O3 Security detects and blocks CVE-2009-4492 exploitation at runtime via eBPF exploit-chain detection and L7 egress monitoring, even on unpatched systems.
WEBrick 1.3.1 in Ruby 1.8.6 through patchlevel 383, 1.8.7 through patchlevel 248, 1.8.8dev, 1.9.1 through patchlevel 376, and 1.9.2dev writes data to a log file without sanitizing non-printable…
Description
WEBrick 1.3.1 in Ruby 1.8.6 through patchlevel 383, 1.8.7 through patchlevel 248, 1.8.8dev, 1.9.1 through patchlevel 376, and 1.9.2dev writes data to a log file without sanitizing non-printable characters, which might allow remote attackers to modify a window's title, or possibly execute arbitrary commands or overwrite files, via an HTTP request containing an escape sequence for a terminal emulator.
Affected Products
webrickruby-langResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Ruby 1.9.1 - WEBrick 'Terminal Escape Sequence in Logs' Command Injection
by evilaliv3 · Jan 11, 2010
Detection & mitigation playbook
Vendor / applianceDetect
Inventory every ruby-lang webrick deployment and check each version against the affected-products list above. Because the exploit targets the running system rather than your application code, also watch for exploitation at the network and runtime layer — O3 flags the exploit behaviour from runtime telemetry and egress traffic even before a vulnerable build is confirmed.
Remediation status
No patch has shipped for CVE-2009-4492 yet — track the ruby-lang webrick advisory for a fixed release and apply the workarounds below in the meantime.
Mitigate without a patch
Cut exposure now: restrict the management/admin interface to trusted networks, segment the device, and apply the vendor's recommended configuration mitigations and any WAF/IPS signature. O3's runtime protection blocks the exploit chain at execution, holding the line on unpatched or end-of-life systems until you can patch.
How O3 protects you
O3 detects and blocks CVE-2009-4492 exploitation at runtime: eBPF exploit-chain detection, plus L7 egress monitoring that catches the post-exploitation callback and severs the attacker's outbound channel.
Tailored to CVE-2009-4492. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2009-4492 being exploited in your environment?
O3's eBPF runtime sensors and L7 egress monitoring detect and block the CVE-2009-4492 exploit chain at execution — protecting unpatched and end-of-life systems until the vendor patch is applied.