HTTPKiller: Apache HTTP Server Denial of Service Tool
Threat Type:
IntelliShield: Security Activity Bulletin
IntelliShield ID:
23983
Version:
3
First Published:
2011 August 22 17:02 GMT
Last Published:
2011 August 26 13:59 GMT
Port:
Not Available
Urgency:
Possible Use
Credibility:
Confirmed
Severity:
Mild Damage
Version Summary:
Additional information is available regarding exploits that target the Apache Range Retrieval Request processing denial of service vulnerability.
Description
A publicly available exploit tool that exploits a vulnerability in Apache HTTP Server could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected system. Apache has reported that active use of this tool has been observed.
The vulnerability, documented in IntelliShield alert 24004, exists because the affected software incorrectly processes a Range Retrieval Request header that is received via an HTTP request. Due to the flaw, upon receiving a request with a 0-byte range or overlapping byte ranges, the affected software erroneously allocates a bucket for each byte requested and stores them in a brigade.
The tool allows an unauthenticated, remote attacker to send malicious HTTP requests to the affected system, triggering excessive memory consumption that could lead to a DoS condition.
Administrators are advised to contact the vendor regarding future updates and releases. Until updates can be applied, administrators are advised to configure connection throttling or filtering of repetitive, abusive connection requests.
Apache has confirmed the vulnerability in a security announcement. Updated software is not available; however, Apache has released approved workarounds.
Apache has released a security announcement at the following link: CVE-2011-3192
Signatures
Cisco Systems Cisco Intrusion Prevention System (IPS) 6.0
Version 2, August 25, 2011, 2:27 PM: Additional technical information that describes the Apache Range Retrieval Request processing denial of service vulnerability is available.
Version 1, August 22, 2011, 12:02 PM: Apache contains a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service condition on a targeted system. Updates are not available.
The security vulnerability applies to the following combinations of products.
Primary Products:
Apache Software Foundation
Apache HTTP Server
2.0.50 Base | 2.0.51 Base | 2.0.52 Base | 2.0.53 Base | 2.0.54 Base | 2.0.55 Base | 2.0.56 Base | 2.0.57 Base | 2.0.58 Base | 2.0.59 Base | 2.0.61 Base | 2.0.63 Base | 2.2 .0, .1, .10, .11, .12, .13, .14, .15, .16, .2, .3, .4, .6, .7, .8, .9
Associated Products:
N/A
Alerts and bulletins on the Cisco Security Intelligence Operations Portal are highlighted by analysts in the
Cisco Threat Operations Center and represent a subset of the comprehensive content that is available through Cisco Security IntelliShield Alert Manager Service.
This customizable threat and vulnerability alert service provides security staff with access to timely, accurate, and credible information about threats and vulnerabilities that may affect their environment. Cisco is pleased to offer a free trial of the service.
To register for full access, please visit the IntelliShield trial registration page.
LEGAL DISCLAIMER The urgency and severity ratings of this alert are not tailored to individual users; users may value alerts differently based upon their network configurations and circumstances. THE ALERT, AND INFORMATION CONTAINED THEREIN, ARE PROVIDED ON AN "AS IS" BASIS AND DO NOT IMPLY ANY KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. YOUR USE OF THE ALERT, AND INFORMATION CONTAINED THEREIN, OR MATERIALS LINKED FROM THE ALERT, IS AT YOUR OWN RISK. INFORMATION IN THIS ALERT AND ANY RELATED COMMUNICATIONS IS BASED ON OUR KNOWLEDGE AT THE TIME OF PUBLICATION AND IS SUBJECT TO CHANGE WITHOUT NOTICE. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE ALERTS AT ANY TIME.
