ari Vatsvakurudzi vezvekuchengetedzwa kweQualys vakaratidza kushushikana kwakanyanya (CVE-2021-3156) mune sudo zvinoshandiswa, iyo yakagadzirirwa kuronga kuraira kuitirwa vamwe vashandisi.
Kunetseka inobvumira isina kuvimbwa kuwana nemidzi rombo. Dambudziko inogona kushandiswa nechero mushandisi, zvisinei nekuvapo mumapoka ehurongwa uye kuvapo kwekupinda mu / etc / sudoers faira.
Kurwiswa hakudi kuti upinde password yemushandisi, ndiko kuti, kushomeka kunogona kushandiswa nemunhu wekunze kukwidziridza ropafadzo pahurongwa mushure mekukanganiswa kwazvakaitwa mune isina rombo rakanaka (kusanganisira izvo zvakatanga nemushandisi "hapana").
Kutsvaga kusagadzikana pane yako system, ingo mhanyisa rairo "sudoedit -s /" uye kusagadzikana kuripo kana mhosho meseji inotanga na "sudoedit:" inoratidzwa.
Nezve kusagadzikana
Dambudziko iri rakaonekwa kubva muna Chikunguru 2011 uye rinokonzerwa nehupfu hwakawanda mukubata kwemavara ekupukunyuka mavara mumiparamende inoitirwa kuita mirairo mune Shell mode. Iyo shell modhi inogoneswa nekutsanangudza iyo "-i" Kana "-s" nharo uye inokonzeresa kuti murairo uitwe kwete zvakananga, asi kuburikidza neyakawedzera shell kufona ne "-c" mureza ("sh -c raira»).
Chinokosha ndechekuti kana iyo sudo yekushandisa ichimhanya zvakajairika, inopukunyuka iwo akasarudzika mavara nekutsanangura iyo "-i" Uye "-s" sarudzo, asi kana iyo sudoedit yekushandisa yatanga, iyo parameter haina kupukunyuka, separse_args () Basa racho rinoisa nharaunda nharaunda ModE_EDIT pachinzvimbo cheMODE_SHELL uye haina kumisazve kukosha kwe "valid_flags".
Uyezve, isina-kupukunyuka hunhu kutapurirana kunogadzira mamiriro ekuti imwe mhosho ioneke mune mutongi, iyo inobvisa mavara ekupukunyuka usati watarisa iyo sudoer mitemo.
Iye mubati zvisirizvo anotsikisa huvepo hwehunhu hwekudzokera shure Pasina kupunyuka kumagumo kwetambo, inofunga kuti kudzoka shure uku kunotiza imwe hunhu uye kuenderera mberi nekuverenga data kupfuura muganho wemutsara, kuikopa mu "user_args" buffer uye kunyora nzvimbo dzekurangarira kunze kwenzira.
Uye zvinotaurwa kuti kana uchiedza kushandisa zvisizvo muudoedit rairo yekuraira, anorwisa anogona kuzadzikiswa kwemutsara unonyorwazve mune iyo data inobata nzira inotevera yebasa.
Pamusoro pekugadzira chishandiso chinorerutsa chokwadi chekuti uyo anorwisa ane masimba akakwana pamusoro pehukuru hwe mushandisi_args buffer, inoenderana nehukuru hwekupokana kwese kwakapfuudzwa, uye zvakare inodzora saizi nezvakanyorwa zve data zvakanyorwa kunze kwe buffer uchishandisa nharaunda nharaunda.
Vanotsvaga kuchengetedzwa kweQualys vakakwanisa kugadzirira zviitwa zvitatu, zvine basa rakanangana nekunyorazve zvemukati meiyo sudo_hook_entry, sevhisi_user uye def_timestampdir zvivakwa:
- Nekubvisa sudo_hook_entry bhanari rakanzi "SYSTEMD_BYPASS_USERDB" rinogona kumhanya semudzi.
- Kuwedzeredza sevhisi_user yakakwanisa kumhanyisa kodhi kodhi semidzi.
- Nekuwedzeredza def_timestampdir, zvaikwanisika kuburitsa zvirimo mune iyo sudo stack, kusanganisira zvakatipatsanura nharaunda, mu / etc / passwd faira, uye uwane kutsiviwa kwemushandisi nemidzi rombo.
Vatsvakurudzi ndaratidza kuti zviito zvinoshanda kuwana zvizere midzi midzi paUbuntu 20.04, Debian 10 uye Fedora 33.
Kunetseka inogona kushandiswa pane mamwe masisitimu anoshanda nekugovera, asi kuongorora kwevaongorori kwaive kwakaganhurirwa kuUbuntu, Debian, naFedora, uyezve zvinonzi zvese shanduro dzerudo 1.8.2 kusvika 1.8.31p2 uye 1.9.0 kusvika 1.9.5p1 muzvigadziriso zvisirizvo zvakakanganiswa. Yakagadziriswa mhinduro mune Sudo 1.9.5p2.
Vatsvakurudzi vakazivisa vagadziri pamberi Distributors izvo zvakatoburitsa mapakeji ekuvandudza nenzira yakabatana: Debian, RHEL, Fedor, Ubuntu, SUSE / openSUSE, Arch Linux, Slackware, Gentoo, uye FreeBSD.
Finalmente kana iwe uchifarira kuziva zvakawanda nezvazvo nezve kushomeka, iwe unogona kutarisa izvo Mune inotevera chinongedzo.