Multiple Unix/Linux Vendor cURL/libcURL Kerberos Authentication Buffer Overflow Vulnerability iDEFENSE Security Advisory 02.21.05: http://www.idefense.com/application/poi/display?type=vulnerabilities February 21, 2005 I. BACKGROUND cURL is a command line tool for transferring files with URL syntax, supporting FTP, FTPS, HTTP, HTTPS, GOPHER, TELNET, DICT, FILE and LDAP. More information about cURL and libcURL is available from: http://curl.haxx.se/ II. DESCRIPTION Remote exploitation of a stack-based buffer overflow in various Unix / Linux vendors' implementation of cURL could allow for arbitrary code execution on the targeted host. An exploitable stack-based buffer overflow condition exists when using Kerberos authentication. The problem specifically exists within the functions Curl_krb_kauth() and krb4_auth() defined in lib/krb4.c. Within these functions a statically allocated stack-based buffer of size 1250, from struct KTEXT_ST.dat, is passed to the Curl_base64_decode() routine defined in lib/base64.c as can be seen here: len = Curl_base64_decode(p, (char *)adat.dat); tmp = Curl_base64_decode(p, (char *)tkt.dat); The Curl_base64_decode() routine relies on the calling function to validate the decoded length. This function base64 decodes and copies data directly from the HTTP reply of a server to the destination buffer, in this case buffer[]. An attacker can construct a long base64 encoded malicious payload that upon decoding will overflow the static buffer and overwrite the saved EIP. This in turn can lead to arbitrary code execution. III. ANALYSIS Sucessful exploitation allows remote attackers to execute arbitary code under the privileges of the target user. Exploitation requires that an attacker either cooerce or force a target to connect to a malicious server using Kerberos authentication. IV. DETECTION iDEFENSE has confirmed the existence of this vulnerability in cURL version 7.12.1. It is suspected that prior versions are affected as well. Any application built using a vulnerable version libcURL will also be affected. V. WORKAROUND Recompile cURL without Kerberos support if it is not needed. VI. VENDOR RESPONSE TBD VII. CVE INFORMATION TBD VIII. DISCLOSURE TIMELINE 12/23/2004 Initial vendor notification - No response 02/10/2005 Secondary vendor notification - No response 02/21/2005 Public disclosure IX. CREDIT infamous41md[at]hotpop.com is credited with this discovery. Get paid for vulnerability research http://www.idefense.com/poi/teams/vcp.jsp X. LEGAL NOTICES Copyright
Multiple Unix/Linux Vendor cURL/libcURL Kerberos Authentication Buffer Overflow Vulnerability iDEFENSE Security Advisory 02.21.05: http://www.idefense.com/application/poi/display?type=vulnerabilities February 21, 2005 I. BACKGROUND cURL is a command line tool for transferring files with URL syntax, supporting FTP, FTPS, HTTP, HTTPS, GOPHER, TELNET, DICT, FILE and LDAP. More information about cURL and libcURL is available from: http://curl.haxx.se/ II. DESCRIPTION Remote exploitation of a stack-based buffer overflow in various Unix / Linux vendors' implementation of cURL could allow for arbitrary code execution on the targeted host. An exploitable stack-based buffer overflow condition exists when using Kerberos authentication. The problem specifically exists within the functions Curl_krb_kauth() and krb4_auth() defined in lib/krb4.c. Within these functions a statically allocated stack-based buffer of size 1250, from struct KTEXT_ST.dat, is passed to the Curl_base64_decode() routine defined in lib/base64.c as can be seen here: len = Curl_base64_decode(p, (char *)adat.dat); tmp = Curl_base64_decode(p, (char *)tkt.dat); The Curl_base64_decode() routine relies on the calling function to validate the decoded length. This function base64 decodes and copies data directly from the HTTP reply of a server to the destination buffer, in this case buffer[]. An attacker can construct a long base64 encoded malicious payload that upon decoding will overflow the static buffer and overwrite the saved EIP. This in turn can lead to arbitrary code execution. III. ANALYSIS Sucessful exploitation allows remote attackers to execute arbitary code under the privileges of the target user. Exploitation requires that an attacker either cooerce or force a target to connect to a malicious server using Kerberos authentication. IV. DETECTION iDEFENSE has confirmed the existence of this vulnerability in cURL version 7.12.1. It is suspected that prior versions are affected as well. Any application built using a vulnerable version libcURL will also be affected. V. WORKAROUND Recompile cURL without Kerberos support if it is not needed. VI. VENDOR RESPONSE TBD VII. CVE INFORMATION TBD VIII. DISCLOSURE TIMELINE 12/23/2004 Initial vendor notification - No response 02/10/2005 Secondary vendor notification - No response 02/21/2005 Public disclosure IX. CREDIT infamous41md[at]hotpop.com is credited with this discovery. Get paid for vulnerability research http://www.idefense.com/poi/teams/vcp.jsp X. LEGAL NOTICES Copyright © 2005 iDEFENSE, Inc. Permission is granted for the redistribution of this alert electronically. It may not be edited in any way without the express written consent of iDEFENSE. If you wish to reprint the whole or any part of this alert in any other medium other than electronically, please email customerservice@idefense.com for permission. Disclaimer: The information in the advisory is believed to be accurate at the time of publishing based on currently available information. Use of the information constitutes acceptance for use in an AS IS condition. There are no warranties with regard to this information. Neither the author nor the publisher accepts any liability for any direct, indirect, or consequential loss or damage arising from use of, or reliance on, this information.
Another one: Multiple Unix/Linux Vendor cURL/libcURL NTLM Authentication Buffer Overflow Vulnerability iDEFENSE Security Advisory 02.21.05: http://www.idefense.com/application/poi/display?type=vulnerabilities February 21, 2005 I. BACKGROUND cURL is a command line tool for transferring files with URL syntax, supporting FTP, FTPS, HTTP, HTTPS, GOPHER, TELNET, DICT, FILE and LDAP. More information about cURL and libcURL is available from: http://curl.haxx.se/ II. DESCRIPTION Remote exploitation of a stack-based buffer overflow in various Unix / Linux vendors' implementation of cURL could allow for arbitrary code execution on the targeted host. An exploitable stack-based buffer overflow condition exists when using NT Lan Manager (NTLM) authentication. The problem specifically exists within Curl_input_ntlm() defined in lib/http_ntlm.c. Within this function an unsigned stack-based character array of size 256, buffer[], is passed to the Curl_base64_decode() routine defined in lib/base64.c as can be seen here: size_t size = Curl_base64_decode(header, (char *)buffer); The Curl_base64_decode() routine relies on the calling function to validate the decoded length. This function base64 decodes and copies data directly from the HTTP reply of a server to the destination buffer, in this case buffer[]. An attacker can construct a long base64 encoded malicious payload that upon decoding will overflow the 256 byte static buffer and overwrite the saved EIP. This in turn can lead to arbitrary code execution. III. ANALYSIS Sucessful exploitation allows remote attackers to execute arbitary code under the privileges of the target user. Exploitation requires that an attacker either cooerce or force a target to connect to a malicious server using NTLM authentication. IV. DETECTION iDEFENSE has confirmed the existence of this vulnerability in cURL version 7.12.1. It is suspected that prior versions are affected as well. Any application built using a vulnerable version libcURL will also be affected. V. WORKAROUND Replace that static buffer allocation on line 106 in lib/http_ntlm.c: unsigned char buffer[256]; With a dynamic buffer allocation: unsigned char *buffer = (unsigned char *)malloc(strlen(header)); and recompile cURL. VI. VENDOR RESPONSE TBD VII. CVE INFORMATION TBD VIII. DISCLOSURE TIMELINE 12/21/2004 Initial vendor notification - No response 02/10/2005 Secondary vendor notification - No response 02/21/2005 Public disclosure IX. CREDIT infamous41md[at]hotpop.com is credited with this discovery. Get paid for vulnerability research http://www.idefense.com/poi/teams/vcp.jsp X. LEGAL NOTICES Copyright
Another one: Multiple Unix/Linux Vendor cURL/libcURL NTLM Authentication Buffer Overflow Vulnerability iDEFENSE Security Advisory 02.21.05: http://www.idefense.com/application/poi/display?type=vulnerabilities February 21, 2005 I. BACKGROUND cURL is a command line tool for transferring files with URL syntax, supporting FTP, FTPS, HTTP, HTTPS, GOPHER, TELNET, DICT, FILE and LDAP. More information about cURL and libcURL is available from: http://curl.haxx.se/ II. DESCRIPTION Remote exploitation of a stack-based buffer overflow in various Unix / Linux vendors' implementation of cURL could allow for arbitrary code execution on the targeted host. An exploitable stack-based buffer overflow condition exists when using NT Lan Manager (NTLM) authentication. The problem specifically exists within Curl_input_ntlm() defined in lib/http_ntlm.c. Within this function an unsigned stack-based character array of size 256, buffer[], is passed to the Curl_base64_decode() routine defined in lib/base64.c as can be seen here: size_t size = Curl_base64_decode(header, (char *)buffer); The Curl_base64_decode() routine relies on the calling function to validate the decoded length. This function base64 decodes and copies data directly from the HTTP reply of a server to the destination buffer, in this case buffer[]. An attacker can construct a long base64 encoded malicious payload that upon decoding will overflow the 256 byte static buffer and overwrite the saved EIP. This in turn can lead to arbitrary code execution. III. ANALYSIS Sucessful exploitation allows remote attackers to execute arbitary code under the privileges of the target user. Exploitation requires that an attacker either cooerce or force a target to connect to a malicious server using NTLM authentication. IV. DETECTION iDEFENSE has confirmed the existence of this vulnerability in cURL version 7.12.1. It is suspected that prior versions are affected as well. Any application built using a vulnerable version libcURL will also be affected. V. WORKAROUND Replace that static buffer allocation on line 106 in lib/http_ntlm.c: unsigned char buffer[256]; With a dynamic buffer allocation: unsigned char *buffer = (unsigned char *)malloc(strlen(header)); and recompile cURL. VI. VENDOR RESPONSE TBD VII. CVE INFORMATION TBD VIII. DISCLOSURE TIMELINE 12/21/2004 Initial vendor notification - No response 02/10/2005 Secondary vendor notification - No response 02/21/2005 Public disclosure IX. CREDIT infamous41md[at]hotpop.com is credited with this discovery. Get paid for vulnerability research http://www.idefense.com/poi/teams/vcp.jsp X. LEGAL NOTICES Copyright © 2005 iDEFENSE, Inc. Permission is granted for the redistribution of this alert electronically. It may not be edited in any way without the express written consent of iDEFENSE. If you wish to reprint the whole or any part of this alert in any other medium other than electronically, please email customerservice@idefense.com for permission. Disclaimer: The information in the advisory is believed to be accurate at the time of publishing based on currently available information. Use of the information constitutes acceptance for use in an AS IS condition. There are no warranties with regard to this information. Neither the author nor the publisher accepts any liability for any direct, indirect, or consequential loss or damage arising from use of, or reliance on, this information.
This issue is now public.
CCing maintainer.
http://curl.haxx.se/ libcurl NTLM Buffer Overflow 22 February 2005 As was posted to bugtraq, all versions of curl that supports NTLM has this flaw. The fix. It requires a malicious server to send an unexpectedly long NTLM response header to trigger. (No, we were not contacted nor notified about this problem before they went public.) I'll be away for a week now but I'll put together a new release when I get back. CAN-2005-0490 _______________ Link is given to the following fix: http://cool.haxx.se/cvs.cgi/curl/lib/http_ntlm.c.diff?r1=1.36&r2=1.37 A bug was posted for the kerberos issue at http://sourceforge.net/tracker/index.php?func=detail&aid=1149607&group_id=976&atid=100976 Work seems to have also been done on that issue I'd say after a quick look to the CVS repo.
CAN-2005-0940 Ubuntu Security Notice USN-86-1 We should look for patches somewhere
7.13.1 is out : http://curl.haxx.se/mail/archive-2005-03/0036.html liquidx: please bump
sorry .. i've just only got back to dev'ing after a long break. curl has been bumped but not in stable yet. will report back when i've got that done.
Alastair arch teams will mark stable for you. http://www.gentoo.org/security/en/vulnerability-policy.xml Arch teams please test and mark curl-7.13.1 stable.
curl and pycurl stable on ppc.
stable on amd64
stable on ppc64
sparc stable.
Stable on alpha.
marked stable on x86 already, liquidx, pls comment on bug next time curl-7.13.1.ebuild revision 1.5 date: 2005/03/10 11:29:14; author: liquidx; state: Exp; lines: +2 -2 stable for x86 (Portage version: 2.0.51.19)
Stable on mips.
Stable on hppa thanks to vapie.
GLSA 200503-20 arm, s390 please remember to mark stable to benifit from the GLSA.
