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.
A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().
The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.
| Link | Tags |
|---|---|
| https://www.viestintavirasto.fi/en/cybersecurity/vulnerabilities/2017/haavoittuvuus-2017-037.html | issue tracking third party advisory patch |
| http://www.securityfocus.com/bid/101590 | issue tracking vdb entry third party advisory |
| https://security.gentoo.org/glsa/201711-06 | issue tracking third party advisory vendor advisory |
| http://www.debian.org/security/2017/dsa-4008 | issue tracking third party advisory vendor advisory |
| https://www.synology.com/support/security/Synology_SA_17_62_Wget | |
| http://git.savannah.gnu.org/cgit/wget.git/commit/?id=ba6b44f6745b14dce414761a8e4b35d31b176bba | issue tracking third party advisory patch |
| http://www.securitytracker.com/id/1039661 | issue tracking vdb entry third party advisory |
| https://access.redhat.com/errata/RHSA-2017:3075 | vendor advisory |