CVE-2017-13090 wget heap smash

The retr.c:fd_read_body() function is called when processing OK responses. When the response is sent chunked in wget before 1.19.2, the chunk parser uses strtol() to read each chunk's length, but doesn't check that the chunk length is a non-negative number. The code then tries to read the chunk in pieces of 8192 bytes by using the MIN() macro, but ends up passing the negative chunk length to retr.c:fd_read(). As fd_read() takes an int argument, the high 32 bits of the chunk length are discarded, leaving fd_read() with a completely attacker controlled length argument. The attacker can corrupt malloc metadata after the allocated buffer. Reproduction To reproduce, use two terminals. In the first terminal: $ nc -l -p 8080 <wget-heap-smash.reply In the second terminal: $ wget http://127.0.0.1:8080/foo Depending on how wget is compiled, this will either simply segfault or complain about the heap being corrupted. External Links https://nvd.nist.gov/vuln/detail/CVE-2017-13090 http://git.savannah.gnu.org/cgit/wget.git/commit?id=ba6b44f6745b14dce414761a8e4b35d31b176bba http://www.debian.org/security/2017/dsa-4008 http://www.securityfocus.com/bid/101590 http://www.securitytracker.com/id/1039661 https://www.viestintavirasto.fi/en/cybersecurity/vulnerabilities/2017/haavoittuvuus-2017-037.html