CVE-2019-0053 PoC — Junos OS: Insufficient validation of environment variables in telnet client may lead to stack-based buffer overflow

Title:Junos OS: Insufficient validation of environment variables in telnet client may lead to stack-based buffer overflow (CVE-2019-0053)
Description:Insufficient validation of environment variables in the telnet client supplied in Junos OS can lead to stack-based buffer overflows, which can be exploited to bypass veriexec restrictions on Junos OS. A stack-based overflow is present in the handling of environment variables when connecting via the telnet client to remote telnet servers. This issue only affects the telnet client — accessible from the CLI or shell — in Junos OS. Inbound telnet services are not affected by this issue. This issue affects: Juniper Networks Junos OS: 12.3 versions prior to 12.3R12-S13; 12.3X48 versions prior to 12.3X48-D80; 14.1X53 versions prior to 14.1X53-D130, 14.1X53-D49; 15.1 versions prior to 15.1F6-S12, 15.1R7-S4; 15.1X49 versions prior to 15.1X49-D170; 15.1X53 versions prior to 15.1X53-D237, 15.1X53-D496, 15.1X53-D591, 15.1X53-D69; 16.1 versions prior to 16.1R3-S11, 16.1R7-S4; 16.2 versions prior to 16.2R2-S9; 17.1 versions prior to 17.1R3; 17.2 versions prior to 17.2R1-S8, 17.2R2-S7, 17.2R3-S1; 17.3 versions prior to 17.3R3-S4; 17.4 versions prior to 17.4R1-S6, 17.4R2-S3, 17.4R3; 18.1 versions prior to 18.1R2-S4, 18.1R3-S3; 18.2 versions prior to 18.2R1-S5, 18.2R2-S2, 18.2R3; 18.2X75 versions prior to 18.2X75-D40; 18.3 versions prior to 18.3R1-S3, 18.3R2; 18.4 versions prior to 18.4R1-S2, 18.4R2.

A patched Arch Linux PKGBUILD to address CVE-2019-0053 (buffer overflow). Downloads and applies a (currently) unreleased patch from upstream.

inetutils hasn't been updated in 5 years, and neither has the official Arch package. A patch has been released that addresses CVE-2019-0053 (buffer overflow exploit from the use of sprintf instead of snprintf), but there's no official release in sight.

Honestly, there's a lot more wrong with using telnet than just buffer exploits, but this was a high urgency issue that took 10 minutes to address. Waiting on a response from the official maintainers right now, but this repo will do for the meantime.

 [4.0K]  /data/pocs/673d8f6e251c7c799b81cf471b9548401a480f54
├── [5.1K]  0001-telnetd-Fix-buffer-overflows.patch
├── [2.6K]  0037-telnet-Validate-supplied-environment-variables.-CVE-.patch
├── [ 371]  inetutils.install
├── [ 15K]  PKGBUILD
├── [ 504]  README.md
└── [ 127]  telnetd.pam

0 directories, 6 files