var-200505-0162
Vulnerability from variot
Heap-based buffer overflow in the env_opt_add function in telnet.c for various BSD-based Telnet clients allows remote attackers to execute arbitrary code via responses that contain a large number of characters that require escaping, which consumers more memory than allocated. A flaw in the OpenSSL library could allow a remote attacker to cause a denial of service on an affected application. The gzip program contains a buffer overflow vulnerability that may allow an attacker to execute arbitrary code or create a denial-of-service condition. Multiple RSA implementations fail to properly handle RSA signatures. This vulnerability may allow an attacker to forge RSA signatures. Included with many products telnet Clients env_opt_add() There is a vulnerability that causes a buffer overflow when certain input data including escape characters is processed due to improper bounds checking in the function.Configured by a third party telnet Guided or crafted the target user to log in to the server Web By displaying the page, arbitrary code may be executed with the user's authority. Multiple vendors' Telnet client applications are reported prone to a remote buffer-overflow vulnerability. This vulnerability reportedly occurs in the 'env_opt_add()' function in the 'telnet.c' source file, which is apparently common source for all the affected vendors.
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TITLE: gzip Multiple Vulnerabilities
SECUNIA ADVISORY ID: SA21996
VERIFY ADVISORY: http://secunia.com/advisories/21996/
CRITICAL: Moderately critical
IMPACT: DoS, System access
WHERE:
From remote
SOFTWARE: gzip 1.x http://secunia.com/product/4220/
DESCRIPTION: Tavis Ormandy has reported some vulnerabilities in gzip, which can be exploited by malicious people to cause a DoS (Denial of Service) and potentially compromise a vulnerable system.
1) A boundary error within the "make_table()" function in unlzh.c can be used to modify certain stack data. tricking a user or automated system into unpacking a specially crafted archive file. tricking a user or automated system into unpacking a specially crafted "pack" archive file.
3) A buffer overflow within the "make_table()" function of gzip's LZH support can be exploited to cause a DoS and potentially to compromise a vulnerable system by e.g. tricking a user or automated system into unpacking an archive containing a specially crafted decoding table.
4) A NULL pointer dereference within the "huft_build()" function and an infinite loop within the LZH handling can be exploited to cause a DoS by e.g. tricking a user or automated system into unpacking a specially crafted archive file.
The vulnerabilities have been reported in version 1.3.5. Other versions may also be affected.
SOLUTION: Do not unpack untrusted archive files.
PROVIDED AND/OR DISCOVERED BY: Tavis Ormandy, Google Security Team
ORIGINAL ADVISORY: http://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=204676
OTHER REFERENCES: US-CERT VU#554780: http://www.kb.cert.org/vuls/id/554780
US-CERT VU#381508: http://www.kb.cert.org/vuls/id/381508
US-CERT VU#773548: http://www.kb.cert.org/vuls/id/773548
US-CERT VU#933712: http://www.kb.cert.org/vuls/id/933712
US-CERT VU#596848 http://www.kb.cert.org/vuls/id/596848
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. BACKGROUND
The TELNET protocol allows virtual network terminals to be connected to over the internet. The initial description of the telnet protocol was given in RFC854 in May 1983. Since then there have been many extra features added including encryption.
II.
The vulnerability specifically exists in the env_opt_add() function of telnet.c. A buffer of a fixed size (256 bytes) is allocated to store the result of the processing this function performs on network input. If this buffer is not large enough to contain the string, the buffer is expanded by a further 256 bytes. This size is sufficient for most well formed input, as the buffer passed as input to the affected function is limited to the same size. However, due to the way the telnet protocol escapes certain characters, it is possible to increase the length of the output by including a large run of characters which need escaping. This can allow the 256 byte input buffer to expand to a maximum of 512 bytes in the allocated storage buffer. If, after expanding the buffer by 256 bytes, the buffer is still not large enough to contain the input, a heap based buffer overflow occurs, which is exploitable on at least some affected platforms.
III. It may be possible to automatically launch the telnet command from a webpage, for example: