http://bugzilla.opensuse.org/show_bug.cgi?id=1173974 Bug ID: 1173974 Summary: VUL-1: CVE-2020-14315: bsdiff: X41 D-Sec GmbH Security Advisory X41-2020-006: Memory Corruption Vulnerability in bspatch Classification: openSUSE Product: openSUSE Distribution Version: Leap 15.1 Hardware: Other URL: https://smash.suse.de/issue/263055/ OS: Other Status: NEW Severity: Minor Priority: P5 - None Component: Other Assignee: screening-team-bugs@suse.de Reporter: meissner@suse.com QA Contact: security-team@suse.de Found By: Security Response Team Blocker: --- CVE-2020-14315 X41 D-Sec GmbH Security Advisory X41-2020-006: Memory Corruption Vulnerability in bspatch From: X41 D-Sec GmbH Advisories Date: Thu, 9 Jul 2020 18:41:37 +0200 -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 X41 D-SEC GmbH Security Advisory: X41-2020-006 Advisory X41-2020-006: Memory Corruption Vulnerability in bspatch ================================================================= Severity Rating: High Confirmed Affected Versions: Colin Percival's bsdiff 4.3 Confirmed Patched Versions: FreeBSD's bsdiff (https://svnweb.freebsd.org/base/head/usr.bin/bsdiff/bspatch/bspatch.c) Vendor: Colin Percival Vendor URL: https://www.daemonology.net/bsdiff/ Vendor Reference: None Vector: Patch file Credit: X41 D-SEC GmbH, Luis Merino Status: Public CVE: CVE-2020-14315 CWE: 119 CVSS Score: N/A CVSS Vector: N/A Advisory-URL: https://www.x41-dsec.de/lab/advisories/x41-2020-006-bspatch/ Summary and Impact ================== A memory corruption vulnerability is present in bspatch as shipped in Colin Percival’s bsdiff tools version 4.3. Insufficient checks when handling external inputs allows an attacker to bypass the sanity checks in place and write out of a dynamically allocated buffer boundaries. Even though the patching procedure is usually combined with integrity and authenticity checks, an attacker that is able to deliver a malicious patch can cause heap corruption in the process running bspatch code, when the authenticity checks happen after applying the patches. Depending on their ability to control and shape the heap state before and during the processing of a malicious patch file, remote code execution may be achieved. This has already been demonstrated (https://gist.github.com/anonymous/e48209b03f1dd9625a992717e7b89c4f#file-free...) as a proof-of-concept exploit in 2016 by an anonymous author against the FreeBSD bspatch implementation on 32bit architectures. This issue was initially reported for bspatch in bsdiff “as used in Apple OS X before 10.11.6 and other products” with CVE-2014-9862 by an anonymous researcher and was partially addressed by several projects, including Android (https://android.googlesource.com/platform/external/bsdiff/+/4d054795b673855e...), ChromiumOS (https://bugs.chromium.org/p/chromium/issue/detail?id=372525) and FreeBSD (https://www.freebsd.org/security/advisories/FreeBSD-SA-16:25.bspatch.asc) during 2016. This initial batch of fixes prevented the attack via negative control values. Nevertheless, huge control values that would integer overflow the sanity checks and allow an attacker writing out of bounds were not fixed. A subsequent patch was released by FreeBSD (https://www.freebsd.org/security/advisories/FreeBSD-SA-16:29.bspatch.asc) addressing the remaining issues together with additional hardening. Unfortunately, most of bspatch copies didn’t port this fix. It is worth mentioning that bsdiff 4.3, as hosted at Colin Percival’s bsdiff website https://www.daemonology.net/bsdiff/, still ships a copy of bspatch.c vulnerable to these issues via both negative and huge control values. All the Linux distributions we have checked shipping bsdiff are building from this sources, with some of them applying the partial fix initially released. Product Description =================== bsdiff and bspatch are tools for building and applying patches to binary files. They provide an efficient way to apply binary patches for applications update mechanisms. Analysis ======== Insufficient checks when calculating the buffer offset and size of write operations allows writing out of a heap allocated buffer boundaries. - - - ------------------8newsize) errx(1,"Corrupt patch\n"); /* Read diff string */ lenread = BZ2_bzRead(&dbz2err, dpfbz2, new + newpos, ctrl[0]); - - - ------------------8 References: http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2020-14315 http://seclists.org/oss-sec/2020/q3/18 https://www.freebsd.org/security/advisories/FreeBSD-SA-16:29.bspatch.asc https://www.freebsd.org/security/advisories/FreeBSD-SA-16:25.bspatch.asc https://svnweb.freebsd.org/base/head/usr.bin/bsdiff/bspatch/bspatch.c https://www.x41-dsec.de/lab/advisories/x41-2020-006-bspatch/ https://bugs.chromium.org/p/chromium/issue/detail?id=372525 -- You are receiving this mail because: You are on the CC list for the bug.