dointisme/cve-2020-8597CVE-2020-8597 데모: pppd의 EAP 핸들러에서의 버퍼 오버플로우에 대한 시연으로, 익스플로잇 분석, 스택 카나리 우회 논의, 교육용 보안 연구를 위한 메모리 맵 디버깅을 포함합니다.
ppp 2.4.2부터 2.4.8까지의 pppd에 있는 eap.c 파일은 eap_request 및 eap_response 함수에 rhostname 버퍼 오버플로우가 존재합니다.
"EAP: unauthenticated peer name"을 충분히 길게 얻으면 (내 클라이언트는 255로 제한하는 것 같지만), 버퍼 오버플로우를 수행할 수 있습니다.
여전히 Stack Canaries를 우회해야 하므로, 충돌(crash)이 가장 가능성이 높습니다.
RELRO STACK CANARY NX PIE RPATH RUNPATH Symbols FORTIFY Fortified Fortifiable FILE
Full RELRO Canary found NX enabled PIE enabled No RPATH No RUNPATH No Symbols Yes 12 22 /usr/sbin/pppd
ppp 및 pppoe (PPP over Ethernet)에 영향을 미칩니다.
출처 (패치):
https://github.com/paulusmack/ppp/commit/8d7970b8f3db727fe798b65f3377fe6787575426
*** buffer overflow detected ***: pppd terminated
======= Backtrace: =========
/lib/x86_64-linux-gnu/libc.so.6(+0x777e5)[0x7fea131337e5]
/lib/x86_64-linux-gnu/libc.so.6(__fortify_fail+0x5c)[0x7fea131d515c]
/lib/x86_64-linux-gnu/libc.so.6(+0x117160)[0x7fea131d3160]
pppd[0x42a858]
pppd(main+0x95f)[0x40981f]
/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf0)[0x7fea130dc830]
pppd(_start+0x29)[0x409db9]
======= Memory map: ========
00400000-00448000 r-xp 00000000 fd:01 11540966 /usr/sbin/pppd
00648000-00649000 r--p 00048000 fd:01 11540966 /usr/sbin/pppd
00649000-0064f000 rw-p 00049000 fd:01 11540966 /usr/sbin/pppd
0064f000-0069b000 rw-p 00000000 00:00 0
01c7b000-01c9c000 rw-p 00000000 00:00 0 [heap]
7fea12666000-7fea1267c000 r-xp 00000000 fd:01 13898255 /lib/x86_64-linux-gnu/libgcc_s.so.1
7fea1267c000-7fea1287b000 ---p 00016000 fd:01 13898255 /lib/x86_64-linux-gnu/libgcc_s.so.1
7fea1287b000-7fea1287c000 rw-p 00015000 fd:01 13898255 /lib/x86_64-linux-gnu/libgcc_s.so.1
7fea1287c000-7fea12887000 r-xp 00000000 fd:01 13908799 /lib/x86_64-linux-gnu/libnss_files-2.23.so
7fea12887000-7fea12a86000 ---p 0000b000 fd:01 13908799 /lib/x86_64-linux-gnu/libnss_files-2.23.so
7fea12a86000-7fea12a87000 r--p 0000a000 fd:01 13908799 /lib/x86_64-linux-gnu/libnss_files-2.23.so
7fea12a87000-7fea12a88000 rw-p 0000b000 fd:01 13908799 /lib/x86_64-linux-gnu/libnss_files-2.23.so
7fea12a88000-7fea12a8e000 rw-p 00000000 00:00 0
7fea12a8e000-7fea12a99000 r-xp 00000000 fd:01 13908792 /lib/x86_64-linux-gnu/libnss_nis-2.23.so
7fea12a99000-7fea12c98000 ---p 0000b000 fd:01 13908792 /lib/x86_64-linux-gnu/libnss_nis-2.23.so
7fea12c98000-7fea12c99000 r--p 0000a000 fd:01 13908792 /lib/x86_64-linux-gnu/libnss_nis-2.23.so
7fea12c99000-7fea12c9a000 rw-p 0000b000 fd:01 13908792 /lib/x86_64-linux-gnu/libnss_nis-2.23.so
7fea12c9a000-7fea12cb0000 r-xp 00000000 fd:01 13908797 /lib/x86_64-linux-gnu/libnsl-2.23.so
7fea12cb0000-7fea12eaf000 ---p 00016000 fd:01 13908797 /lib/x86_64-linux-gnu/libnsl-2.23.so
7fea12eaf000-7fea12eb0000 r--p 00015000 fd:01 13908797 /lib/x86_64-linux-gnu/libnsl-2.23.so
7fea12eb0000-7fea12eb1000 rw-p 00016000 fd:01 13908797 /lib/x86_64-linux-gnu/libnsl-2.23.so
7fea12eb1000-7fea12eb3000 rw-p 00000000 00:00 0
7fea12eb3000-7fea12ebb000 r-xp 00000000 fd:01 13908803 /lib/x86_64-linux-gnu/libnss_compat-2.23.so
7fea12ebb000-7fea130ba000 ---p 00008000 fd:01 13908803 /lib/x86_64-linux-gnu/libnss_compat-2.23.so
7fea130ba000-7fea130bb000 r--p 00007000 fd:01 13908803 /lib/x86_64-linux-gnu/libnss_compat-2.23.so
7fea130bb000-7fea130bc000 rw-p 00008000 fd:01 13908803 /lib/x86_64-linux-gnu/libnss_compat-2.23.so
7fea130bc000-7fea1327c000 r-xp 00000000 fd:01 13908802 /lib/x86_64-linux-gnu/libc-2.23.so
7fea1327c000-7fea1347c000 ---p 001c0000 fd:01 13908802 /lib/x86_64-linux-gnu/libc-2.23.so
7fea1347c000-7fea13480000 r--p 001c0000 fd:01 13908802 /lib/x86_64-linux-gnu/libc-2.23.so
7fea13480000-7fea13482000 rw-p 001c4000 fd:01 13908802 /lib/x86_64-linux-gnu/libc-2.23.so
7fea13482000-7fea13486000 rw-p 00000000 00:00 0
7fea13486000-7fea13489000 r-xp 00000000 fd:01 13908787 /lib/x86_64-linux-gnu/libdl-2.23.so
7fea13489000-7fea13688000 ---p 00003000 fd:01 13908787 /lib/x86_64-linux-gnu/libdl-2.23.so
7fea13688000-7fea13689000 r--p 00002000 fd:01 13908787 /lib/x86_64-linux-gnu/libdl-2.23.so
7fea13689000-7fea1368a000 rw-p 00003000 fd:01 13908787 /lib/x86_64-linux-gnu/libdl-2.23.so
7fea1368a000-7fea1368c000 r-xp 00000000 fd:01 13908804 /lib/x86_64-linux-gnu/libutil-2.23.so
7fea1368c000-7fea1388b000 ---p 00002000 fd:01 13908804 /lib/x86_64-linux-gnu/libutil-2.23.so
7fea1388b000-7fea1388c000 r--p 00001000 fd:01 13908804 /lib/x86_64-linux-gnu/libutil-2.23.so
7fea1388c000-7fea1388d000 rw-p 00002000 fd:01 13908804 /lib/x86_64-linux-gnu/libutil-2.23.so
7fea1388d000-7fea13896000 r-xp 00000000 fd:01 13908796 /lib/x86_64-linux-gnu/libcrypt-2.23.so
7fea13896000-7fea13a95000 ---p 00009000 fd:01 13908796 /lib/x86_64-linux-gnu/libcrypt-2.23.so
7fea13a95000-7fea13a96000 r--p 00008000 fd:01 13908796 /lib/x86_64-linux-gnu/libcrypt-2.23.so
7fea13a96000-7fea13a97000 rw-p 00009000 fd:01 13908796 /lib/x86_64-linux-gnu/libcrypt-2.23.so
7fea13a97000-7fea13ac5000 rw-p 00000000 00:00 0
7fea13ac5000-7fea13aeb000 r-xp 00000000 fd:01 13908788 /lib/x86_64-linux-gnu/ld-2.23.so
7fea13cb5000-7fea13cba000 rw-p 00000000 00:00 0
7fea13ce5000-7fea13ce6000 rw-p 00000000 00:00 0
7fea13ce6000-7fea13cea000 rw-s 00000000 00:17 983 /run/pppd2.tdb
7fea13cea000-7fea13ceb000 r--p 00025000 fd:01 13908788 /lib/x86_64-linux-gnu/ld-2.23.so
7fea13ceb000-7fea13cec000 rw-p 00026000 fd:01 13908788 /lib/x86_64-linux-gnu/ld-2.23.so
7fea13cec000-7fea13ced000 rw-p 00000000 00:00 0
7ffc7c941000-7ffc7c962000 rw-p 00000000 00:00 0 [stack]
7ffc7c9b3000-7ffc7c9b6000 r--p 00000000 00:00 0 [vvar]
7ffc7c9b6000-7ffc7c9b8000 r-xp 00000000 00:00 0 [vdso]
ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0 [vsyscall]