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ARC Insecure Temporary File Creation
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SUMMARY
<http://sourceforge.net/projects/arc/> ARC is "used to create and
maintain file archives. An archive is a group of files collected together
into one file in such a way that the individual files may be recovered
intact".
A vulnerability in ARC is caused due to temporary file being created
insecurely. The temporary file used for archive creation could be read by
untrusted users.
DETAILS
Vulnerable Systems:
* ARC versions 5.21j and prior.
Vulnerable code:
arc.c :
210 /* see where temp files go */
211 #if !_MTS
212 arctemp = calloc(1, STRLEN);
213 if (!(arctemp2 = envfind("ARCTEMP")))
214 arctemp2 = envfind("TMPDIR");
215 if (arctemp2) {
216 strcpy(arctemp, arctemp2);
217 n = strlen(arctemp);
218 if (arctemp[n - 1] != CUTOFF)
219 arctemp[n] = CUTOFF;
220 }
221 #if UNIX
222 else strcpy(arctemp, "/tmp/");
223 #endif
224 #if !MSDOS
225 {
226 static char tempname[] = "AXXXXXX";
227 strcat(arctemp, mktemp(tempname));
228 }
229 #else
230 strcat(arctemp, "$ARCTEMP");
231 #endif
232 #else
233 guinfo("SHFSEP ", gotinf);
234 sepchr[0] = gotinf[0];
235 guinfo("SCRFCHAR", gotinf);
236 tmpchr[0] = gotinf[0];
237 arctemp = "-$$$";
238 arctemp[0] = tmpchr[0];
239 #endif
240 arctemp2 = NULL;
241
242 #if !UNIX
243 /* avoid any case problems with arguments */
244
245 for (n = 1; n < num; n++) /* for each argument */
246 upper(arg[n]); /* convert it to uppercase */
247 #else
248 /* avoid case problems with command options */
249 upper(arg[1]); /* convert to uppercase */
250 #endif
251
252 /* create archive names, supplying defaults */
253 #if UNIX
254 if (!stat(arg[2],&sbuf)) {
255 if ((sbuf.st_mode & S_IFMT) == S_IFDIR)
256 makefnam(arg[2],".arc",arcname);
257 else
258 strcpy(arcname,arg[2]);
259 } else
260 makefnam(arg[2],".arc",arcname);
261 #else
262 makefnam(arg[2], ".ARC", arcname);
263 #endif
Take a look on a the right off temporary files in /tmp :
-rw-r--r-- 1 root root 1564 Sep 5 10:28 A3C6Zs4.arc
The file should not be world readable.
The same problem exists in marc.c
ADDITIONAL INFORMATION
The information has been provided by <mailto:exploits@zataz.net> ZATAZ
Audits.
The original article can be found at:
<http://www.zataz.net/adviso/arc-09052005.txt>
http://www.zataz.net/adviso/arc-09052005.txt
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