A heap-based buffer overflow, when processing chunked encoded HTTP responses, was found in wget. By tricking an unsuspecting user into connecting to a malicious HTTP server, an attacker could exploit this flaw to potentially execute arbitrary code.
A heap-based buffer overflow vulnerability was found in HTTP protocol handling, potentially allowing a code execution.
The retr.c:fd_read_body() function is called when processing OK responses. When the response is sent chunked, 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.
Created attachment 1342259 [details]
Name: the GNU Wget project
Looks like this was introduced via
RHEL6 does not have this code.
This issue affects the versions of wget as shipped with Red Hat Enterprise Linux 7. This issue did not affect the versions of wget as shipped with Red Hat Enterprise Linux 5 and 6.
Created wget tracking bugs for this issue:
Affects: fedora-all [bug 1506720]
This issue has been addressed in the following products:
Red Hat Enterprise Linux 7
Via RHSA-2017:3075 https://access.redhat.com/errata/RHSA-2017:3075