Bug 853321 (CVE-2011-5129)
| Summary: | CVE-2011-5129 xchat: Heap-based buffer overflow (crash, ACE) via long response string | ||
|---|---|---|---|
| Product: | [Other] Security Response | Reporter: | Kurt Seifried <kseifried> |
| Component: | vulnerability | Assignee: | Stefan Cornelius <scorneli> |
| Status: | CLOSED NOTABUG | QA Contact: | |
| Severity: | low | Docs Contact: | |
| Priority: | low | ||
| Version: | unspecified | CC: | caillon, jlieskov, jrb, security-response-team |
| Target Milestone: | --- | Keywords: | Security |
| Target Release: | --- | ||
| Hardware: | All | ||
| OS: | Linux | ||
| Whiteboard: | |||
| Fixed In Version: | Doc Type: | Bug Fix | |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: | ||
| Last Closed: | 2012-09-05 06:37:02 UTC | Type: | --- |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Embargoed: | |||
| Bug Depends On: | |||
| Bug Blocks: | 853449 | ||
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Description
Kurt Seifried
2012-08-31 04:12:13 UTC
National Vulnerability Database (NVD) entry: Heap-based buffer overflow in XChat 2.8.9 and earlier allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via a long response string. References: http://www.securityfocus.com/bid/50820 http://www.osvdb.org/77629 http://www.exploit-db.com/exploits/18159/ http://packetstormsecurity.org/files/107312/xchat-dos.txt https://bugzilla.novell.com/show_bug.cgi?id=778254 I dont think this is really a flaw at all. Looking at xchat source, the following should prevent any buffer overflow.
static gboolean
server_read (GIOChannel *source, GIOCondition condition, server *serv)
...
...
default:
serv->linebuf[serv->pos] = lbuf[i];
if (serv->pos >= (sizeof (serv->linebuf) - 1))
fprintf (stderr,
"*** XCHAT WARNING: Buffer overflow - shit server!\n");
else
serv->pos++;
The data read from the server is stored in lbuf, whose size is 2050 bytes. Data is read via:
len = _SSL_recv (serv->ssl, lbuf, sizeof (lbuf) - 2);
The total data which is read from the server really is just 2048 bytes.
Later in the loop each bye from lbuf is copied into the serv->linebuf buffer and the position of the copied byte is stored in serv->pos.
serv->pos may not be zero when the data is copied into serv->linebuf.
In the above piece of code, if serv->pos (The place where data needs to be copied into the serv->linebuf, stack buffer), exceeds the size of lbuf, it prints a warning message on stderr and does not increment serv->pos.
So any new data to be read from lbuf, is copied into the last value of serv->pos, leading to no buffer overwrite.
Statement: This bug is not a security issue. For detailed explanation, refer to: https://bugzilla.redhat.com/show_bug.cgi?id=853321#c4 |